Podcast
Questions and Answers
Which of the following is NOT a fundamental attribute shared by all living things?
Which of the following is NOT a fundamental attribute shared by all living things?
- Respiration
- Reproduction
- Photosynthesis (correct)
- Sensitivity
Stable environmental conditions, such as consistent temperature and pH levels, are crucial for the survival of living organisms.
Stable environmental conditions, such as consistent temperature and pH levels, are crucial for the survival of living organisms.
True (A)
Besides an energy source, what other crucial substance is required for biochemical reactions and cellular transport within living organisms?
Besides an energy source, what other crucial substance is required for biochemical reactions and cellular transport within living organisms?
Liquid water
The process of converting glucose into ATP to power cellular activities is known as __________.
The process of converting glucose into ATP to power cellular activities is known as __________.
If an organism thrives in extremely high salinity conditions, which cellular adaptation is MOST crucial?
If an organism thrives in extremely high salinity conditions, which cellular adaptation is MOST crucial?
Which of the following is NOT a tenet of the cell theory?
Which of the following is NOT a tenet of the cell theory?
Prokaryotic cells contain membrane-bound organelles such as mitochondria and endoplasmic reticulum.
Prokaryotic cells contain membrane-bound organelles such as mitochondria and endoplasmic reticulum.
What is the region in a prokaryotic cell where DNA is located called?
What is the region in a prokaryotic cell where DNA is located called?
The cell wall of prokaryotes is made of peptidoglycan, while the __________ is made of polysaccharides.
The cell wall of prokaryotes is made of peptidoglycan, while the __________ is made of polysaccharides.
Match the scientist with their contribution to the cell theory:
Match the scientist with their contribution to the cell theory:
Which of the following is NOT found in eukaryotic cells?
Which of the following is NOT found in eukaryotic cells?
Why are there no large unicellular organisms?
Why are there no large unicellular organisms?
Extremely Difficult: Calculate the surface area to volume ratio of a hypothetical, perfectly spherical cell with a radius of 100 micrometers. Express your answer rounded to the nearest whole number.
Extremely Difficult: Calculate the surface area to volume ratio of a hypothetical, perfectly spherical cell with a radius of 100 micrometers. Express your answer rounded to the nearest whole number.
What happens to the surface area to volume ratio (SA:V) as a cube increases in size?
What happens to the surface area to volume ratio (SA:V) as a cube increases in size?
A cell with a larger cytoplasm has a higher surface area to volume ratio compared to a cell with smaller cytoplasm.
A cell with a larger cytoplasm has a higher surface area to volume ratio compared to a cell with smaller cytoplasm.
Why do larger organisms often require specialized transport systems like a circulatory system?
Why do larger organisms often require specialized transport systems like a circulatory system?
For a cube with side length L, the surface area is calculated by $SA = 6L^2$, and the volume is calculated by $V= ______$.
For a cube with side length L, the surface area is calculated by $SA = 6L^2$, and the volume is calculated by $V= ______$.
Match the organism with its typical surface area to volume ratio adaptation:
Match the organism with its typical surface area to volume ratio adaptation:
What is the relationship between a cell's metabolic needs and its ability to transport materials as the volume of the cell increases?
What is the relationship between a cell's metabolic needs and its ability to transport materials as the volume of the cell increases?
The rate at which nutrients enter and wastes leave a cell is generally directly proportional to cell size.
The rate at which nutrients enter and wastes leave a cell is generally directly proportional to cell size.
Consider two cubes: Cube A has a side length of 2 units, and Cube B has a side length of 4 units. What best describes the relationship between their surface area to volume ratios?
Consider two cubes: Cube A has a side length of 2 units, and Cube B has a side length of 4 units. What best describes the relationship between their surface area to volume ratios?
What is the primary function of microvilli in cells lining the small intestine?
What is the primary function of microvilli in cells lining the small intestine?
An obligate endosymbiont can survive independently outside of its host cell.
An obligate endosymbiont can survive independently outside of its host cell.
What is the main function of ribosomes?
What is the main function of ribosomes?
The process by which cells break down non-functioning organelles is called __________.
The process by which cells break down non-functioning organelles is called __________.
Match the following organelles with their primary functions:
Match the following organelles with their primary functions:
Which of the following is NOT a function of the cytoskeleton?
Which of the following is NOT a function of the cytoskeleton?
Red blood cells contain numerous mitochondria to support their high energy demands.
Red blood cells contain numerous mitochondria to support their high energy demands.
What type of molecule primarily composes the cell membrane?
What type of molecule primarily composes the cell membrane?
__________ proteins span the width of the plasma membrane.
__________ proteins span the width of the plasma membrane.
Which of the following is the primary function of the enzyme catalase found in peroxisomes?
Which of the following is the primary function of the enzyme catalase found in peroxisomes?
Glycolipids on the plasma membranes play a role in cell to cell communication.
Glycolipids on the plasma membranes play a role in cell to cell communication.
What are the two main components of the plasma membrane?
What are the two main components of the plasma membrane?
The rough ER is characterized by the presence of __________ on its surface.
The rough ER is characterized by the presence of __________ on its surface.
Which of the following best describes the function of cholesterol within the cell membrane?
Which of the following best describes the function of cholesterol within the cell membrane?
How does the arrangement of phospholipids in the cell membrane contribute to its barrier function, and what property of the phospholipid molecules is crucial for this arrangement?
How does the arrangement of phospholipids in the cell membrane contribute to its barrier function, and what property of the phospholipid molecules is crucial for this arrangement?
Which of the following structures is NOT found in prokaryotic cells?
Which of the following structures is NOT found in prokaryotic cells?
According to the original cell theory, all cells arise spontaneously.
According to the original cell theory, all cells arise spontaneously.
What is the primary component of the cell walls in prokaryotic cells?
What is the primary component of the cell walls in prokaryotic cells?
The region in a prokaryotic cell where DNA is located is called the ______.
The region in a prokaryotic cell where DNA is located is called the ______.
Match the following scientists with their contribution to cell theory:
Match the following scientists with their contribution to cell theory:
What characteristic distinguishes eukaryotic cells from prokaryotic cells?
What characteristic distinguishes eukaryotic cells from prokaryotic cells?
Which of the following cell types can change their shape?
Which of the following cell types can change their shape?
What is the main reason there are no enormous unicellular organisms?
What is the main reason there are no enormous unicellular organisms?
Which factor directly affects the rate of diffusion across a cell membrane due to its influence on molecular movement?
Which factor directly affects the rate of diffusion across a cell membrane due to its influence on molecular movement?
Channel proteins, unlike carrier proteins, change shape to facilitate the transport of substances across the cell membrane.
Channel proteins, unlike carrier proteins, change shape to facilitate the transport of substances across the cell membrane.
What property of the phospholipid tails in the cell membrane's bilayer allows it to be fluid and flexible?
What property of the phospholipid tails in the cell membrane's bilayer allows it to be fluid and flexible?
Proteins that span the entire width of the plasma membrane are known as transmembrane or ______ proteins.
Proteins that span the entire width of the plasma membrane are known as transmembrane or ______ proteins.
Match each protein function with its role in the cell membrane:
Match each protein function with its role in the cell membrane:
Which type of protein is directly involved in cell-to-cell communication via the formation of gap junctions?
Which type of protein is directly involved in cell-to-cell communication via the formation of gap junctions?
Enzymes alter themselves permanently while catalyzing biochemical reactions.
Enzymes alter themselves permanently while catalyzing biochemical reactions.
What molecule in the cell membrane helps to maintain stability and reduce fluidity at normal body temperatures?
What molecule in the cell membrane helps to maintain stability and reduce fluidity at normal body temperatures?
What is the main function of glycoproteins and glycolipids on the cell surface?
What is the main function of glycoproteins and glycolipids on the cell surface?
Facilitated diffusion requires the use of special protein _______ to move molecules across the cell membrane.
Facilitated diffusion requires the use of special protein _______ to move molecules across the cell membrane.
Which of the following cellular components is NOT present in mature red blood cells?
Which of the following cellular components is NOT present in mature red blood cells?
Active transport moves molecules from an area of high concentration to an area of low concentration.
Active transport moves molecules from an area of high concentration to an area of low concentration.
The breakdown of non-functioning cell organelles through digestion within the cell is known as ________.
The breakdown of non-functioning cell organelles through digestion within the cell is known as ________.
Match the organelle with its primary function:
Match the organelle with its primary function:
Which of the following is a key function of the smooth endoplasmic reticulum?
Which of the following is a key function of the smooth endoplasmic reticulum?
Ribosomes are enclosed within a membrane.
Ribosomes are enclosed within a membrane.
What two types of molecules compose ribosomes?
What two types of molecules compose ribosomes?
The organelle responsible for producing ribosomal RNA (rRNA) is the ________.
The organelle responsible for producing ribosomal RNA (rRNA) is the ________.
Which of the components of the cytoskeleton is primarily responsible for cell movement?
Which of the components of the cytoskeleton is primarily responsible for cell movement?
Peroxisomes use the enzyme catalase to break down hydrogen peroxide into water and oxygen.
Peroxisomes use the enzyme catalase to break down hydrogen peroxide into water and oxygen.
What is one key difference between cilia and flagella in eukaryotic cells?
What is one key difference between cilia and flagella in eukaryotic cells?
The process by which large molecules are transported across the cell membrane using vesicles is called ________ transport.
The process by which large molecules are transported across the cell membrane using vesicles is called ________ transport.
Which of the following factors does NOT affect the rate of diffusion across a cell membrane?
Which of the following factors does NOT affect the rate of diffusion across a cell membrane?
Which of the following is the correct chemical equation for cellular respiration?
Which of the following is the correct chemical equation for cellular respiration?
A plant bends towards a window to capture more sunlight. Which attribute of living things does this BEST exemplify?
A plant bends towards a window to capture more sunlight. Which attribute of living things does this BEST exemplify?
Why is liquid water considered essential for life as we know it?
Why is liquid water considered essential for life as we know it?
A scientist discovers a new organism in a deep-sea vent that respires sulfur instead of oxygen. Which of the fundamental requirements for life would this organism MOST challenge?
A scientist discovers a new organism in a deep-sea vent that respires sulfur instead of oxygen. Which of the fundamental requirements for life would this organism MOST challenge?
Which of the following processes is the MOST direct example of respiration in living organisms?
Which of the following processes is the MOST direct example of respiration in living organisms?
A population of bacteria doubles in size every 20 minutes under ideal conditions. Which characteristic of life does this BEST illustrate?
A population of bacteria doubles in size every 20 minutes under ideal conditions. Which characteristic of life does this BEST illustrate?
Which of the following organelles is responsible for modifying and packaging proteins into transport vesicles?
Which of the following organelles is responsible for modifying and packaging proteins into transport vesicles?
An immune response is triggered when a cell does not display the correct ________ on its surface.
An immune response is triggered when a cell does not display the correct ________ on its surface.
What is the primary role of transport proteins or 'pumps' in active transport?
What is the primary role of transport proteins or 'pumps' in active transport?
How does the oxidation of fatty acids in peroxisomes contribute to cellular metabolism?
How does the oxidation of fatty acids in peroxisomes contribute to cellular metabolism?
What is the role of the sodium-potassium pump in maintaining the resting membrane potential in neurons?
What is the role of the sodium-potassium pump in maintaining the resting membrane potential in neurons?
Which component of the cytoskeleton is primarily responsible for providing mechanical support and maintaining cell shape?
Which component of the cytoskeleton is primarily responsible for providing mechanical support and maintaining cell shape?
Which of the following best describes the function of ribosomes?
Which of the following best describes the function of ribosomes?
If a poison prevents the Golgi apparatus from functioning, what cellular process will be MOST directly affected?
If a poison prevents the Golgi apparatus from functioning, what cellular process will be MOST directly affected?
What is the significance of the highly folded inner membrane (cristae) of the mitochondria?
What is the significance of the highly folded inner membrane (cristae) of the mitochondria?
If a cell were unable to perform autophagy, what would be the most likely consequence?
If a cell were unable to perform autophagy, what would be the most likely consequence?
Consider a cell with a high concentration of hydrophobic waste products. Which organelle would likely be most active in detoxifying these substances?
Consider a cell with a high concentration of hydrophobic waste products. Which organelle would likely be most active in detoxifying these substances?
Which of the following is a direct result of the breakdown of glycogen in the smooth endoplasmic reticulum (ER)?
Which of the following is a direct result of the breakdown of glycogen in the smooth endoplasmic reticulum (ER)?
How do cilia and flagella contribute to the function of eukaryotic cells?
How do cilia and flagella contribute to the function of eukaryotic cells?
Which of the following observations would indicate that a particular cell is highly active and requires a significant amount of energy?
Which of the following observations would indicate that a particular cell is highly active and requires a significant amount of energy?
Which of the following cellular structures is primarily responsible for synthesizing proteins?
Which of the following cellular structures is primarily responsible for synthesizing proteins?
According to the modern cell theory, which statement is MOST accurate regarding the origin of cells?
According to the modern cell theory, which statement is MOST accurate regarding the origin of cells?
Which of the following structures is NOT a characteristic of prokaryotic cells?
Which of the following structures is NOT a characteristic of prokaryotic cells?
What is the primary role of the capsule found in some prokaryotic cells?
What is the primary role of the capsule found in some prokaryotic cells?
Why can some cells, like white blood cells and amoebas, change their shape?
Why can some cells, like white blood cells and amoebas, change their shape?
A cell's ability to efficiently exchange substances with its environment is MOST directly related to:
A cell's ability to efficiently exchange substances with its environment is MOST directly related to:
A spherical cell with a radius of 5 micrometers has a surface area to volume ratio that allows for efficient nutrient exchange. If the cell's radius doubles to 10 micrometers, what happens to the surface area to volume ratio?
A spherical cell with a radius of 5 micrometers has a surface area to volume ratio that allows for efficient nutrient exchange. If the cell's radius doubles to 10 micrometers, what happens to the surface area to volume ratio?
Which of the following BEST explains why larger, multicellular organisms require specialized transport systems, such as a circulatory system?
Which of the following BEST explains why larger, multicellular organisms require specialized transport systems, such as a circulatory system?
How do cells lining the small intestine compensate for their relatively large size to maintain efficient nutrient absorption?
How do cells lining the small intestine compensate for their relatively large size to maintain efficient nutrient absorption?
Which of the following statements BEST describes the relationship between cell size and the rate of nutrient and waste transport?
Which of the following statements BEST describes the relationship between cell size and the rate of nutrient and waste transport?
Which scientist provided evidence that all cells come from pre-existing cells, challenging a prevailing idea at the time?
Which scientist provided evidence that all cells come from pre-existing cells, challenging a prevailing idea at the time?
A researcher discovers a new unicellular organism. Initial observations reveal the presence of ribosomes, a cell wall, and a circular chromosome. Further analysis is MOST needed to determine if the organism also contains:
A researcher discovers a new unicellular organism. Initial observations reveal the presence of ribosomes, a cell wall, and a circular chromosome. Further analysis is MOST needed to determine if the organism also contains:
How does the presence of microvilli on the surface of certain cells enhance their functionality?
How does the presence of microvilli on the surface of certain cells enhance their functionality?
Based on the principles of surface area to volume ratio, which cellular adaptation would be MOST beneficial for maximizing the exchange of substances between a cell and its environment?
Based on the principles of surface area to volume ratio, which cellular adaptation would be MOST beneficial for maximizing the exchange of substances between a cell and its environment?
Considering the limitations imposed by the surface area to volume ratio, what evolutionary advantage might multicellularity provide to organisms?
Considering the limitations imposed by the surface area to volume ratio, what evolutionary advantage might multicellularity provide to organisms?
Which of the following transport mechanisms relies on a change in the shape of the transport protein to facilitate movement across the cell membrane?
Which of the following transport mechanisms relies on a change in the shape of the transport protein to facilitate movement across the cell membrane?
How does an increase in temperature affect the rate of diffusion, and why?
How does an increase in temperature affect the rate of diffusion, and why?
In the context of osmosis, what condition describes a cell surrounded by a solution with a higher solute concentration compared to the inside of the cell?
In the context of osmosis, what condition describes a cell surrounded by a solution with a higher solute concentration compared to the inside of the cell?
Why does the cell membrane's structure allow red blood cells to squeeze through narrow capillaries?
Why does the cell membrane's structure allow red blood cells to squeeze through narrow capillaries?
Which of the following is a primary function of integral proteins in the cell membrane?
Which of the following is a primary function of integral proteins in the cell membrane?
Proteins embedded in the cell membrane can serve as receptors for signaling molecules. What is the immediate consequence of a signaling molecule binding to its receptor?
Proteins embedded in the cell membrane can serve as receptors for signaling molecules. What is the immediate consequence of a signaling molecule binding to its receptor?
How do membrane proteins contribute to cell identity?
How do membrane proteins contribute to cell identity?
Enzymes facilitate biochemical reactions by lowering activation energy. What property of enzymes ensures that they catalyze only specific reactions?
Enzymes facilitate biochemical reactions by lowering activation energy. What property of enzymes ensures that they catalyze only specific reactions?
Cholesterol is a component of animal cell membranes. What role does it play in maintaining membrane stability and fluidity?
Cholesterol is a component of animal cell membranes. What role does it play in maintaining membrane stability and fluidity?
Which statement accurately describes the arrangement and properties of phospholipids in the cell membrane?
Which statement accurately describes the arrangement and properties of phospholipids in the cell membrane?
How does the binding of a signaling molecule to a receptor protein typically initiate a cellular response?
How does the binding of a signaling molecule to a receptor protein typically initiate a cellular response?
What is the role of a channel protein in the cell membrane?
What is the role of a channel protein in the cell membrane?
How do glycoproteins and glycolipids contribute to a cell's ability to interact with its environment?
How do glycoproteins and glycolipids contribute to a cell's ability to interact with its environment?
How does the fluidity of the phospholipid bilayer affects the function of the cell membrane?
How does the fluidity of the phospholipid bilayer affects the function of the cell membrane?
What is the role of membrane proteins in intercellular joinings?
What is the role of membrane proteins in intercellular joinings?
Flashcards
Energy Source
Energy Source
Organisms need energy to power metabolic processes.
Liquid Water
Liquid Water
Essential for biochemical reactions and cellular transport in organisms.
Chemical Building Blocks
Chemical Building Blocks
Elements like carbon, oxygen, nitrogen, and hydrogen are essential for life.
Stable Environmental Conditions
Stable Environmental Conditions
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MRS GREN
MRS GREN
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Cell Theory
Cell Theory
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Prokaryotes
Prokaryotes
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Eukaryotes
Eukaryotes
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Capsule
Capsule
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Ribosomes
Ribosomes
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Surface Area to Volume Ratio
Surface Area to Volume Ratio
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Nucleus
Nucleus
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Anton van Leeuwenhoek
Anton van Leeuwenhoek
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Surface Area of a Cube
Surface Area of a Cube
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Volume of a Cube
Volume of a Cube
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Decrease in SA:V Ratio
Decrease in SA:V Ratio
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Metabolic Needs and Cell Size
Metabolic Needs and Cell Size
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Transport Systems in Larger Organisms
Transport Systems in Larger Organisms
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Single-Celled Organisms
Single-Celled Organisms
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Human Exchange Surfaces
Human Exchange Surfaces
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Cell Size Limitation
Cell Size Limitation
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Microvilli Function
Microvilli Function
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Endosymbiont
Endosymbiont
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Obligate Endosymbiont
Obligate Endosymbiont
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Mitochondria
Mitochondria
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Endoplasmic Reticulum (ER)
Endoplasmic Reticulum (ER)
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Golgi Apparatus
Golgi Apparatus
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Lysosomes
Lysosomes
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Cytoskeleton
Cytoskeleton
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Phospholipid Bilayer
Phospholipid Bilayer
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Roles of Cell Membrane Proteins
Roles of Cell Membrane Proteins
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Cholesterol in Membrane
Cholesterol in Membrane
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Cell Identity
Cell Identity
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Cytosol (Cytoplasm)
Cytosol (Cytoplasm)
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Plasma Membrane
Plasma Membrane
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Endoplasmic Reticulum
Endoplasmic Reticulum
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The Three Tenets of Cell Theory
The Three Tenets of Cell Theory
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Temperature and Diffusion Rate
Temperature and Diffusion Rate
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Particle Size and Diffusion
Particle Size and Diffusion
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Facilitated Diffusion
Facilitated Diffusion
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Channel Proteins
Channel Proteins
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Carrier Proteins
Carrier Proteins
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Integral Membrane Proteins
Integral Membrane Proteins
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Transport Proteins
Transport Proteins
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Receptor Proteins
Receptor Proteins
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Cell Size vs. Transport Rate
Cell Size vs. Transport Rate
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Intestinal Microvilli
Intestinal Microvilli
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Ribosome Function
Ribosome Function
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Nucleus Function
Nucleus Function
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Mitochondria Function
Mitochondria Function
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Endoplasmic Reticulum (ER) Function
Endoplasmic Reticulum (ER) Function
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Golgi Apparatus Function
Golgi Apparatus Function
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Lysosome Function
Lysosome Function
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Peroxisome Function
Peroxisome Function
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Cytoskeleton Function
Cytoskeleton Function
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Microtubule Function
Microtubule Function
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Passive transport
Passive transport
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Energy requirement
Energy requirement
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Water requirement
Water requirement
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Building blocks requirement
Building blocks requirement
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Stable environment need
Stable environment need
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Life Attributes
Life Attributes
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Deoxyribonucleic Acid (DNA)
Deoxyribonucleic Acid (DNA)
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Cell
Cell
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Cellular Origin
Cellular Origin
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Prokaryotic Cells
Prokaryotic Cells
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Nucleoid
Nucleoid
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Capsule (Cell)
Capsule (Cell)
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Cell Wall (Prokaryotic)
Cell Wall (Prokaryotic)
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Plasmids
Plasmids
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Eukaryotic Cells
Eukaryotic Cells
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Cell Shapes
Cell Shapes
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SA:V Ratio
SA:V Ratio
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SA:V Importance
SA:V Importance
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Microvilli
Microvilli
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Robert Hooke
Robert Hooke
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Osmosis
Osmosis
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Hypotonic Environment
Hypotonic Environment
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Hypertonic Environment
Hypertonic Environment
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Hydrophobic Tails
Hydrophobic Tails
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Hydrophilic Heads
Hydrophilic Heads
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Integral Proteins
Integral Proteins
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Transmembrane Proteins
Transmembrane Proteins
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Glycoproteins
Glycoproteins
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Peripheral Proteins
Peripheral Proteins
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Transport (Cell Membrane Role)
Transport (Cell Membrane Role)
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Reception (Cell Membrane Role)
Reception (Cell Membrane Role)
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Anchorage (Cell Membrane Role)
Anchorage (Cell Membrane Role)
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Cell Identity (Cell Membrane Role)
Cell Identity (Cell Membrane Role)
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Peroxisomes
Peroxisomes
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Microtubules
Microtubules
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Microfilaments
Microfilaments
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Cilia
Cilia
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Flagella
Flagella
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Active Transport
Active Transport
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Study Notes
- Cells need an energy source, liquid water, chemical building blocks (carbon, oxygen, nitrogen, hydrogen), and stable environmental conditions to exist.
- Stable environmental conditions include stable pressure, temperature, pH, light intensity, and salinity
Cell Attributes
- All living things share the attributes, Movement, Respiration (converting glucose into ATP), Sensitivity to stimuli to the environment, Growth, Reproduction (sexual or asexual), Excretion, Nutrition (intake of food), and DNA.
Cell Theory (1839)
- Developed by Theodor Schwann and Matthias Schleiden
- All organisms are composed of one or more cells
- The cell is the basic unit of structure and organisation in organisms
- All cells come from pre-existing cells
Early Microscopy
- Anton van Leeuwenhoek invented his own microscope and saw bacteria from dental scraping, calling them "bacteria animalcules".
- Robert Hook invented the name "The cell."
- Robert Hook only saw dead cells and named cells from looking at prison cells
- Robert Remack proved that cells come from pre-existing cells.
- Matthias Schleiden believed that all cells did not come from other cells
Prokaryotes
- Prokaryotes were the first living organisms on earth.
- Prokaryotes lack a nuclear membrane, so they don't have a distinct nucleus.
- Prokaryotes lack membrane-bound organelles and do have ribosomes
Prokaryotic Cell Makeup
- Capsule made of polysaccharides
- Cell wall made of peptidoglycan
- Cell (plasma) controls what enters and leaves the cell
- Large, circular DNA
- Ribosomes synthesise proteins
- Plasmids are smaller pieces of DNA
- Cytosol contains everything in the cell
Eukaryotes
- Eukaryotes have a nuclear membrane (distinct nucleus) and membrane-bound organelles.
- Eukaryotes are larger than prokaryotic cells.
- Examples of eukaryotes are animal, plant, protist, and fungal cells.
- Eukaryotic DNA is found in the nucleus
Cell Shapes
- Cells come in a variety of shapes that reflect various functions
- Some cells, like white blood cells, amoebas, and cancer cells, can change shapes
Surface Area to Volume Ratio
- The surface area to volume ratio (SA:V) measures the balance between surface area and volume.
- The surface area of a cube is calculated using the formula: SA = 6L^2, wherein L = the length of one side.
- The volume of a cube is calculated using the formula: V = L^3.
- As a cube increases in size, volume enlarges faster than the surface area.
- As cells increase in size (larger cytoplasm), surface area and volume increase at unequal rates.
- Internal volume expands faster than the plasma membrane area; therefore cell growth leads to the relative decrease of its plasma membrane. A small SA:V ratio is the result of this
SA:V Ratio
- Single-celled organisms continuously perform chemical reactions, absorb resources such as Oxygen, Glucose and Amino acids, and get rid of waste such as Co^2 .
- Surface area : Volume decreases as objects get larger; bacteria have a high SA:V ratio and can rely on diffusion
Diffusion in Larger Organisms
- Humans cannot rely on diffusion due to a low SA:V ratio, and they have specialized exchange surfaces to increase this ratio.
- As organisms grow larger, the distance molecules must diffuse increases massively, which is why larger organisms use transport systems, such as the circulatory system
Metabolic Needs
- As cell volume increases, metabolic needs increase, requiring increased inputs and outputs across the plasma membrane. Material increases in proportion to the cell's surface area.
- As cell volume increases, metabolic needs increase faster than cell's ability to transport materials. This explains why active metabolic cells are so small.
- The rate at which nutrients enter/wastes leave is generally inverse to cell size (measured in cytoplasm); the larger the cell, the slower the nutrient/waste movement.
- Cells absorbing digested nutrients (small intestine) compensate for decreasing size
- Surface area increase with minimal volume increase by plasma folding on the gut lumen creating microvilli.
Organelles
- Cytosol (cytoplasm)
- Plasma membrane
- Nucleus
- Mitochondria
- Ribosome
- Golgi apparatus
- Endoplasmic reticulum
- Deoxyribonucleic acid - DNA
Obligate Organelle features
- All plant and animal cells contain a nucleus/nuclear membrane, nucleoles, plasma membrane, ribosomes and peroxisomes, cytoskeleton, cytosol, endoplasmic rectiulum, mitochondria, and golgi apparatus
Proteins within cells
- Proteins include haemoglobin, actin and myosin (contractile proteins), insulin and lipase, and antibodies (white blood cells)
Nucleus
- The nucleus houses DNA is enclosed within double walled membrane
- The nucleus controls DNA replication during cell division, initiates gene expression and controls metabolic activities
Nucleolus
- The nucleolus is composed of RNA and not enclosed within a membrane.It produces RNA
Mitochondria
- Mitochondria are for energy production and produce ATP in cellular respiration
- Mitochondria are visible with an electron microscope only; they are a double membrane organelle.
- The more active the cell, the more mitochondria present.
- Mature red blood cells lack mitochondria.
Golgi apparatus
- The Golgi apparatus is a layered structure where proteins from the rough ER get transferred, where proteins are packaged into secretary vesicles
Lysosomes
- Lysosomes are spherical shaped and contain about 50 digestive enzymes
- Lysosomes digest macromolecules within a cell, and perform autophagy (the breakdown of non-functioning cell organelles)
Peroxisomes
- Peroxisomes are used for cellular metabolism and the oxidization of fatty acids
- They break down toxic substances, contain many enzymes, break down hydrogen peroxide via catalysis, and adheres to this equation 2H2O2 (I) → 2H2O (I) + O2 (g)
Cytoskeleton
- The cytoskeleton is a 3D frame work of eukaryotic cells with 3 components
- Functions include: supplying support and strength for the cell, maintaining cell shape and cell mobility, moving cell organelles.
- The cytoskeleton is used for moving chromosomes during cell divisions
Cell membrane
- Some unicellular eukaryotes depend on cilia and flagella to move.
- Flagella are generally singular, and look like a tail.
- However, cillia are shorter and more numerous.
- Functions include: Cell shape, cell mobility, movement of cell organelles, and moving chromosomes during cell divisions 3 components
Cell Membrane features
- The cell membrane is an active and selective barrier that receives messages from outside and transports materials between the intracellular and extra cellular environment
- If a cell doesn't display the correct molecules, an immune response takes place and the cell dies
Plasma Membrane
- The plasma membrane has 2 main components.
- A type of molecule crossing can be determined if it is hydrophilic or hydrophobic, and also by molecule size and concentration gradient
Phospholipid Bilayer
- Consists of two layers with hydrophobic tails facing each other and consists of two fatty acid chains joined to a hydrophilic phosphate The head faces the cytosol.
- At a normal body temperature the proteins are viscous fluids and are fluid, flexible, soft, able to move freely enabling red blood cells to squeeze through capillaries and enabling cells to change shape
Plasma Membrane - proteins
- Proteins can be embedded in the bilayer and move freely within the bilayer.
- Proteins are either Integral or Peripheral
- Integral are Embedded in the phospholipid bilayer and span the width of the plasma membrane. They are transmembrane proteins.
- If carbohydrate groups like sugars are attached to the exposed part of these proteins they are Glycoproteins which can be anchored to the exterior of the plasma membrane by bonding to lipids
- If proteins are indirectly associated with the plasma membrane, its through interactions with integral proteins in the membrane
Cell Membrane and Proteins
- Transport: Trans-membrane proteins allow movement of the hydrophilic substances across the phospholipid bilayer; they can travel through:
- Channel proteins: Open to all molecules to diffuse in to and out of the cell, and These substance are usually small and charged like ions
- Carrier proteins: allow the movement for larger molecules
- Reception
- The cell may uses receptors for signalling molecules which are peptide or amino acid-based molecules. The shape is altered when the singal reachs the protiens
- Anchorage
- Proteins connect the intracellular cytoskeleton to the extracellular matrix
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- Proteins connect the intracellular cytoskeleton to the extracellular matrix. Proteins connect to the cell via collagen fibres and peptidoglycan filaments that have been excreted by cells
- Cell identity
- Proteins mark the as belonging to self.
- They are Glycoproteins, Antigens, and Cell identity tags can signal other cells
- In mammals that let immune System to identify the cells as self via marker proteins from the blood cells
- Glycolipids on the plasma membranes play a role in tissue recognition
- Intercellular joinings
- Proteins connect to hold the tissues together
- They join cells together and facilitate communication between cells. Allowing tissues to have efficient functioning
- Enzymatic activity
- Enymes are Proteins that catalyse reactions by lowering activation energy and bind the substrates and weaken the bonds to initiate the reaction
- The enzyme's specificity can only bind to one and/or two substrates and aren't altered in the prosess
- Facilitating other biochemical pathways, such as the production of ATP
The cell also uses other compounds
- Cholesterol maintains membrane stability and fluidity, whilst reducing membrane fluidity
- Carbohydrates are surface markers allowing identifiers via cytoplasm
- They are used in Glycoproteins for cell identity, or for inter cellular joinings to attach cells to the glycollipids
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Test your knowledge of the fundamental attributes of life, cellular structures, and cell theory. Explore energy requirements, cellular adaptations, and prokaryotic vs. eukaryotic cells. Match scientists with their contributions to cell theory.
