Biology: Basic Functions and Cell Structures

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Questions and Answers

What is the primary function of ribosomes in eukaryotic cells?

Genetic material storage

Photosynthesis

Protein synthesis (correct)

Energy production

Which organelle is responsible for energy production in eukaryotic cells?

Endoplasmic reticulum

Golgi apparatus

Vesicles

Mitochondria (correct)

What characteristic distinguishes plant cells from animal cells?

Large central vacuole (correct)

Ribosomes size

Presence of nucleus

Cell membrane structure

Which structure is noted to have a double membrane and internal stacks of flattened discs in plant cells?

Chloroplasts Signup and view all the answers

Which of the following components is NOT typically found in eukaryotic cells?

Prions Signup and view all the answers

What is a key limitation of electron microscopes compared to light microscopes?

They cannot view living specimens in natural color. Signup and view all the answers

Which characteristic allows stem cells to maintain their population over time?

Self-renewal by continual division. Signup and view all the answers

Where in the human body can stem cells be predominantly found?

In bone marrow, hair follicles, and intestines. Signup and view all the answers

How is the magnification of an image calculated?

Image size divided by actual size. Signup and view all the answers

In which of the following locations would you NOT find stem cells in animals?

Liver tissue. Signup and view all the answers

Which statement accurately describes osmosis?

It is the movement of water from a region of low solute concentration to a region of high solute concentration. Signup and view all the answers

What distinguishes primary active transport from secondary active transport?

Primary active transport uses energy derived directly from ATP hydrolysis. Signup and view all the answers

How can solutions be categorized based on solute concentration?

Isotonic solutions contain equivalent solute concentrations. Signup and view all the answers

Which process allows large or charged molecules to cross the cell membrane?

Facilitated diffusion through specific transmembrane proteins. Signup and view all the answers

Which of the following correctly defines a hypertonic solution?

A solution with higher solute concentration than another solution. Signup and view all the answers

Which of the following functions is NOT integral to the survival of living things?

Adaptation Signup and view all the answers

Which structure is NOT common to all cells?

Mitochondria Signup and view all the answers

In prokaryotic cells, what is the role of pili?

Adhering to surfaces Signup and view all the answers

What size are ribosomes in prokaryotic cells typically characterized as?

70s Signup and view all the answers

Which of the following best differentiates animal cells from plant cells?

Plant cells contain a cell wall Signup and view all the answers

Which of these is true regarding the cytoplasm in all cells?

It provides a medium for metabolic reactions Signup and view all the answers

What characteristic is NOT typical for eukaryotic cells?

Possession of a cell wall in all eukaryotes Signup and view all the answers

Which of the following functions in living organisms is concerned with maintaining a stable internal environment?

Homeostasis Signup and view all the answers

What is the primary function of haemopoietic stem cells in the bone marrow?

They give rise to different types of blood cells. Signup and view all the answers

How do membrane proteins contribute to the cell membrane's function?

They serve as transport points for large and charged substances. Signup and view all the answers

Which characteristic of the phospholipid bilayer restricts the passage of certain substances?

Hydrophobic interactions between the fatty acid tails. Signup and view all the answers

What is the process by which particles move from an area of high concentration to an area of low concentration across the cell membrane?

Passive transport Signup and view all the answers

What role do the hydrophobic tails of phospholipids play in the structure of the cell membrane?

They shield against hydrophilic particles. Signup and view all the answers

Why are epidermal stem cells found in hair follicles considered for regenerative medicine?

They have the ability to regenerate skin tissue. Signup and view all the answers

What property of the phospholipid bilayer allows for the spontaneous breaking and reforming of membranes?

Fluidity and flexibility of individual phospholipids. Signup and view all the answers

What condition is necessary for materials to move freely across the cell membrane?

Low molecular weight of the materials. Signup and view all the answers

Study Notes

Seven Basic Functions of Living Things

Metabolism: Chemical reactions are essential for survival.
Reproduction: Living things produce offspring through sexual or asexual processes.
Sensitivity: Living things respond to internal and external stimuli.
Homeostasis: Maintaining a stable internal environment is crucial.
Excretion: Removal of waste products is necessary.
Nutrition: Exchange of materials and gases with the environment.
Growth/Movement: Living things can move and change shape or size.

Four Common Structures in All Cells

Plasma Membrane: An outer border that maintains an internal chemistry distinct from the exterior.
Genetic Material: Coded instructions control internal cell activities.
Ribosomes: Ribosomes translate coded cell instructions into functional elements.
Cytoplasm: Internal fluid that serves as a medium for metabolic processes.

Prokaryotic Cells

Genetic material resides in the nucleoid region of the cytoplasm.
Ribosomes are small (70S) and responsible for protein synthesis.
All prokaryotes possess a cell wall; some have an outer coating.
Pili are hair-like extensions that aid in adhesion.
Flagella are whip-like projections that enable movement.

Drawings of Prokaryotic Cells

Genetic material should be represented as a loop.
Pili and flagella extend from the cell wall.
Ribosomes are depicted as filled dots labeled 70S.
Flagella are thicker and longer than pili.
Shape should reflect the specific type of bacteria.

Eukaryotic Organisms

Cells contain a nucleus and numerous membrane-bound organelles.
Exhibit a higher level of structural complexity.
Four types: Animal, Plant, Fungi, and Protist.

Eukaryotic Cells

Genetic material is housed within the nucleus, a double-membrane structure.
Ribosomes are larger (80S).
Share membrane-bound organelles: mitochondria, endoplasmic reticulum, Golgi apparatus, vesicles.
Plant cells also possess chloroplasts and a large central vacuole.

Drawings of Eukaryotic Animal Cells

Nucleus should be a double membrane structure with pores.
ER network is connected membranes, while Golgi membranes are unconnected.
Ribosomes are filled dots labeled 80S.
Mitochondria are sausage-shaped with highly folded inner membranes.
Peroxisomes, lysosomes, and secretory vesicles have similar appearances.

Drawings of Plant Cells

A large central vacuole occupies significant space.
Cell wall made of cellulose is a thicker external line.
Chloroplasts are double-membrane structures with internal stacks of flattened discs.

Microscopes

Scientific instruments used to visualize objects too small for the naked eye.
Two main types: Light and Electron.

Light Microscopes

Use glass lenses to bend light and magnify images.
Employ visible light and lenses to magnify mounted specimens.
Include ocular and objective lenses.

Electron Microscopes

Provide much higher magnification and resolution than light microscopes.
Cannot view living specimens in natural color.

Calculating Magnification

Formula: Magnification = Image size ÷ Actual size
Image size and actual size must be in the same units.

Stem Cells

Undifferentiated cells capable of dividing and differentiating into various cell types.
Found in plants and animals.
Plant stem cells are located in meristems (root and shoot tips).
Animal stem cells are found in embryos, adult tissues (bone marrow, blood cells), and cord blood.
Used in treating diseases like leukemia, lymphoma, and diabetes.

Stem Cell Characteristics

Self-renewal: Continuous division and replication.
Potency: Capacity to differentiate into specific cell types.

Stem Cell Niches

Locations where stem cells reside, including bone marrow, hair follicles, heart, intestines, and brain.
Bone marrow: Haemopoietic stem cells give rise to different blood cell types.
Hair follicles: Contain epidermal stem cells involved in hair growth and wound repair.

Cell Membrane

Encloses the cell, separating internal components from the external environment.
Controls internal conditions and maintains homeostasis.
Semi-permeable: Allows only certain materials to cross.
Selective: Regulates the passage of materials that cannot freely cross.

Cell Membrane Components

Phospholipid bilayer: Forms a barrier to certain materials.
- Hydrophobic core limits permeability to large and charged substances.
Membrane proteins: Embedded within the phospholipid bilayer, acting as transport points for large and charged substances.
- Enable the transport of hydrophilic materials according to need.

Phospholipids

Composed of a polar head (glycerol and phosphate) and two non-polar tails (fatty acid chains).
Hydrophilic (water-loving) head region faces outwards.
Hydrophobic (water-repelling) tail region faces inwards.
Spontaneously arrange into a bilayer.

Phospholipid Bilayer Properties

Held together by weak hydrophobic interactions between tails.
Restricts the passage of many substances.
Individual phospholipids move within the bilayer, contributing to fluidity and flexibility.
Allows for spontaneous breaking and reforming of membranes.

Movement Across Biological Membranes

Passive transport: Movement along a concentration gradient (high to low).
- Simple diffusion: Movement of small or lipophilic molecules across the bilayer.
- Osmosis: Movement of water molecules through the bilayer.
- Facilitated diffusion: Movement of large or charged molecules via transmembrane proteins.
Active transport: Movement against a concentration gradient (low to high).
- Primary active transport: Uses ATP hydrolysis to move a molecule against its gradient.
- Secondary active transport: Couples movement of one molecule against its gradient to another molecule moving down an electrochemical gradient.

Osmosis

Special form of simple diffusion involving the movement of free water molecules.
Water acts as a solvent, dissolving polar or charged molecules to create a solution.
Water, being small enough to move between phospholipids, facilitates this movement.
The net movement of water goes from a region of low solute concentration to a region of high solute concentration.
Solutions can be categorized as hypertonic, hypotonic, or isotonic based on their relative solute concentrations.
Hypertonic: Higher solute concentration.
Hypotonic: Lower solute concentration.
Isotonic: Equivalent solute concentrations.

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Description

Explore the seven essential functions of living things and learn about the common structures found in all cells. This quiz covers key concepts such as metabolism, reproduction, and the unique features of prokaryotic cells. Test your knowledge on the building blocks of life!