Biology Chapter: Cell Structure and Function

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Questions and Answers

Which of these is NOT a function of the proteins found in the plasma membrane?

Receiving chemical signals from the environment.

Facilitating the transport of substances into and out of the cell.

Anchoring cytoskeletal fibers.

Serving as the primary structural component of the membrane. (correct)

If a cell lacks a particular enzyme, what is the most likely outcome?

The cell will synthesize an alternative enzyme to perform the function.

The specific reaction that the enzyme catalyzes will proceed at an accelerated rate.

The reaction that relies on the enzyme will not occur. (correct)

The specific reaction will still occur, but at a significantly reduced rate.

Which characteristic is NOT a primary distinction between animal and plant cells?

The presence of a flexible plasma membrane.

The presence of a rigid cellulose cell wall.

The ability to perform respiration

The presence of organelles (correct)

What is the primary reason the body needs to break down disaccharides and polysaccharides into monosaccharides?

Only monosaccharides can be absorbed by the body. (B) Signup and view all the answers

What is the impact of recognition proteins on the immune system's response?

They allow white blood cells to identify foreign cells. (B) Signup and view all the answers

What is the primary purpose of the boot camp, as defined by its organizers?

To bring all students to a uniform level of understanding regarding basic biology concepts. (B) Signup and view all the answers

How does the cytoskeleton contribute to the cell function?

It provides shape, structure and a framework for organelles inside the cell. (B) Signup and view all the answers

Considering the details given, what is the most basic level of life?

Cell (A) Signup and view all the answers

Which of the following should students NOT prioritize when studying the material?

Focusing only on the quizzes to understand the material. (B) Signup and view all the answers

What would be the direct consequence of a cell losing its plasma membrane?

The cell would not be able to maintain intracellular conditions and likely die. (D) Signup and view all the answers

Which characteristic of the plasma membrane is LEAST likely to be found in bacteria living in cold conditions?

A fluid phospholipid bilayer. (B) Signup and view all the answers

Which topic would require students to understand the function of the vocabulary term 'stoma'?

Plant cell interaction with the environment (C) Signup and view all the answers

Which of the following best describes the function of lactase?

Lactase breaks down lactose into glucose and galactose. (D) Signup and view all the answers

According to the material, what will be used to facilitate a hands-on learning experience?

Beads (C) Signup and view all the answers

Which of the following statements accurately describes the way quizzes are to be used, according to the lecture?

The quizzes are to be used for practice and to help the student prepare for tests. (C) Signup and view all the answers

What is emphasized as a crucial step in your learning process during the boot camp?

Actively engaging in the learning process (A) Signup and view all the answers

Why is the plasma membrane described as 'fluid' in the fluid mosaic model?

Because it allows for movement and flexibility due to the nature of its components. (C) Signup and view all the answers

How do double bonds in fatty acid chains affect the structure of lipids?

They cause bends or kinks in the chains, interfering with close packing. (A) Signup and view all the answers

How do saturated and unsaturated fats differ in their molecular structure?

Saturated fats have single bonds only, while unsaturated fats contain one or more double bonds. (C) Signup and view all the answers

Which of the following best describes the arrangement of phospholipids in the plasma membrane?

A bilayer with the hydrophilic phosphate heads facing the cytoplasm and extracellular environment and hydrophobic tails forming a core. (D) Signup and view all the answers

Why is it essential to understand the structure of triglycerides when learning about phospholipids?

Triglycerides serve as a basic reference to understand lipid structure, as they have three fatty acid chains, in contrast to phospholipids' two. (C) Signup and view all the answers

What is the significance of the term 'mosaic' in the context of the fluid mosaic model?

It refers to the membrane being composed of a variety of different molecules, such as lipids and proteins. (C) Signup and view all the answers

How does the presence of unsaturated fatty acids in phospholipids affect the plasma membrane structure?

They create kinks or bends to increase fluidity and space within the membrane. (B) Signup and view all the answers

What would be a primary difference between a phospholipid and a triglyceride, based on their structure?

Phospholipids have a phosphate group and two fatty acid chains, whereas triglycerides have three fatty acid chains. (B) Signup and view all the answers

What distinguishes cilia from flagella in terms of their number and length?

Cilia are short and numerous, while flagella are long and usually one or two per cell. (B) Signup and view all the answers

Which of the following best describes the primary role of spindle fibers during cell division?

They are cytoskeletal structures that facilitate the division process. (D) Signup and view all the answers

What is the primary function of ribosomes within a cell?

To synthesize proteins (A) Signup and view all the answers

Where are centrioles typically found and what is their main role?

Located in the cytoplasm, they act as anchors for spindle fibers. (C) Signup and view all the answers

What is the primary role of lysosomes within a cell, and what is a consequence of their rupture?

They contain enzymes to break down molecules; rupture could lead to cell death. (C) Signup and view all the answers

How does the pH level affect the function of enzymes found within lysosomes?

Enzymes are inactive at the near-neutral pH of the cell. (A) Signup and view all the answers

Which of the following describes the key distinction between eukaryotic and prokaryotic cells?

Eukaryotic cells have a nucleus surrounded by membranes, while prokaryotic cells have a naked nucleus. (B) Signup and view all the answers

What is the location of the nucleolus and what is its relationship to the nucleus?

The nucleolus is a dense body contained within the fluid of the nucleus. (B) Signup and view all the answers

In the context of cellular transport, which of the following best describes the movement of oxygen across a cell membrane?

Simple diffusion down its concentration gradient without requiring energy. (B) Signup and view all the answers

A solution with a concentration of 50 ppm is being compared to another solution with a concentration of 10 ppm. How would the 50 ppm solution be described in relation to the 10 ppm solution?

Hypertonic (A) Signup and view all the answers

If a plant cell is placed in a hypotonic solution, what would be the expected outcome?

The cell will swell, and the central vacuole will become turgid. (D) Signup and view all the answers

Which process accurately describes the movement of water across a selectively permeable membrane from a region of low solute concentration to a region of high solute concentration?

Osmosis, passively following the solute concentration gradient. (A) Signup and view all the answers

Considering a solution with a concentration of 50 mg/L, which statement would apply if the units were changed to parts per million (ppm)?

The concentration would remain the same, as ppm and mg/L are equivalent when dealing with water. (B) Signup and view all the answers

What characteristic distinguishes facilitated diffusion from simple diffusion across a cell membrane?

Facilitated diffusion involves transport proteins, while simple diffusion does not. (A) Signup and view all the answers

What would happen to an animal cell if it was placed in a highly concentrated salt solution?

The cell would shrink as water leaves due to the hypertonic environment. (D) Signup and view all the answers

Which of the following best describes why glucose requires facilitated diffusion to cross the cell membrane?

Glucose cannot move through the phospholipid bilayer due to its polarity; needs transport proteins (A) Signup and view all the answers

What is the primary consequence of placing a plant cell in a hypertonic solution?

Water leaves the cell, causing the cytoplasm to shrink and plasmolysis to occur. (A) Signup and view all the answers

When a plant cell is in an isotonic solution, what is the state of the cell?

Flaccid; balanced water exchange but not turgid. (A) Signup and view all the answers

What is the key role of active transport in cells?

To move substances against their concentration gradient using cellular energy. (C) Signup and view all the answers

How do endocytosis and exocytosis differ in terms of energy requirements as described in the content provided?

Neither endocytosis nor exocytosis requires energy as they are both passive processes. (D) Signup and view all the answers

What distinguishes receptor-mediated endocytosis from other forms of endocytosis?

It requires a specific receptor protein on the cell membrane. (D) Signup and view all the answers

If liver cells have few LDL receptors, what is the DIRECT effect on LDL cholesterol?

LDL levels in the bloodstream increase. (A) Signup and view all the answers

A plant cell loses turgor and wilts. Which cellular process is most directly associated with this observation?

Plasmolysis in a hypertonic environment. (C) Signup and view all the answers

Which of the following contributes to lowering the risk of heart attack, as described by the content?

Increased levels of HDL cholesterol cleaning arteries. (B) Signup and view all the answers

Study Notes

Boot Camp Overview

Boot Camp runs from 10:00 AM to 1:30 PM daily for two days.
There is a break every hour.
The purpose is to review basic biology concepts and bring all students to the same level.

Student Backgrounds

Student backgrounds vary greatly, ranging from recent biology students to those who haven't studied biology for a long time.
Students include graduates with non-science degrees and students with AP Biology or 101 experience.

Key Concepts Covered

Cell Structure, including cell appearance, organelles, and their importance
Cell Transport fundamentals applicable to all living beings
Cell Division, focusing on mitosis and meiosis

Teaching Approach

Emphasize vocabulary related to cell division
Teach basic genetics terms before mitosis/meiosis.
Hands-on learning using, for example, beads for practical understanding.
Provide practice quizzes (not for credit); three attempts allowed
Instructors available during office hours or via email for help.

Organisms and Cells

All organisms are composed of cells.
Cells can be unicellular or multicellular.
The cell is the smallest living unit.
Anything smaller than a cell is not considered living.

Cell Structure (Detailed)

Animal cells have a plasma membrane for protection & flexibility.
Plant cells have a cellulose cell wall for rigidity.
Organelles, such as the nucleus, mitochondria, lysosomes, and ribosomes, are inside cells.
Cellular functions, such as respiration, excretion, reproduction, and metabolism, happen at the cellular level.

Learning Process

Actively participate by reading, asking questions (silly questions are welcome), and writing things down.
Practice for quizzes and exams.
Basic concepts are expected.

Plasma Membrane

The plasma membrane, also known as the cell membrane, is described by the fluid mosaic model.
Phospholipids are similar in structure to triglycerides but have only two fatty acids.
It is composed of glycerol, two fatty acids, and a phosphate.
It has dietary fats called triglycerides.
The phospholipid bilayer forms the membrane, with the phosphate heads facing the cytoplasm and the fatty acid tails in the middle.
The membrane is fluid and composed of multiple types of molecules (proteins and phospholipids), making it a mosaic.

Organic Compounds

Organic compounds have a carbon backbone.
Single bonds create straight chains, double bonds create bends.
Saturated has fatty acids with only single bonds (e.g., butter).
Unsaturated fats contain one or more double bonds (e.g., olive oil).

Enzymes and Functions

Enzymes are biological catalysts speeding up reactions in the body.
Enzymes end in "-ase".
If an enzyme is absent, the reaction does not work.
Example: Lactase breaks down lactose.

Lactose and Breakdown

Lactose is a sugar found in milk.
It breaks down into glucose and galactose.
Lactase is needed to digest lactose.
Lack of lactase can cause problems in the intestine.

Sugar Types

Lactose is a disaccharide.

Polymers and Monomers

Polysaccharides are formed from multiple monosaccharides (e.g., cellulose).
Proteins are polymers made of amino acids.

White Blood Cells and Autoimmune Diseases

White blood cells (WBCs) recognize foreign cells using recognition proteins.
Autoimmune diseases occur when the immune system fails to recognize its own cells.

Cytoskeleton

The cytoskeleton gives the cell its shape and structure through threads and fibers.
Involved in cell division, preventing cell division by targeting spindle fibers.

Cilia and Flagella

Cilia are short, numerous, and helpful for cell movement.
Flagella are long and whip-like, also involved in cell movement

Ribosomes

Ribosomes synthesize proteins.
They can be free or attached to the endoplasmic reticulum.

Centrioles

Centrioles anchor spindle fibers for cell division.
Located within the cytoplasm.

Lysosomes

Lysosomes contain enzymes that break down molecules.
They help neutralize and destroy bacteria.

Organelles (Overview):

The plasma membrane
Cytoskeleton
Ribosomes
Centrioles
Lysosomes
Flagella and cilia
Nucleus - covered in double membrane
Each membrane is a phospholipid bilayer.

Eukaryotic vs. Prokaryotic Cells

Eukaryotic cells have a true nucleus surrounded by membranes
Prokaryotic cells have a "naked" nucleus (not enclosed by a membrane).
Examples: plant/human cells are eukaryotic; bacteria are prokaryotic

Nuclear Envelope, Nucleolus, and Nucleus

The nuclear envelope consists of two membranes with pores for material passage.
The nucleolus is a dense body within the nucleus.
The nucleus is the organelle, not the nucleolus.

DNA Structure

DNA stands for Deoxyribonucleic acid.
DNA is a molecule in the nucleoplasm, an acid.
It contains deoxyribose sugar (with an oxygen removed)

Chromatin and Chromosomes

Chromatin= DNA in uncondensed state.
Chromosomes= DNA in condensed state.
Chromosomes form during cell division.

Human DNA and Chromosomes

Humans have 46 DNA molecules in each cell that condense into 46 chromosomes

Molecules and Genes (Brief)

Molecules are defined (e.g., H2O, CO2, DNA).
Genes determine characteristics, and gene expression determines traits.
Genes are parts of DNA that make proteins.

Zygote Formation

Zygotes are formed from sperm and egg uniting
Zygotes are single cells
Contain 46 DNA molecules (23 from each parent)

Endomembrane System

The endomembrane system is a network of organelles responsible for modifying/storing/transporting cellular products (both inside and outside the cell).

Organelles in the Endomembrane System

Endoplasmic reticulum (Rough and Smooth)
Golgi apparatus
Vacuoles

Ribosomes and Protein Synthesis

Ribosomes synthesize protein.
The protein travels through the rough ER, getting modified.
Protein takes on primary, secondary, and eventually tertiary structure.
Vesicles carry proteins and lipids.

Vesicles

Vesicles bud from the ER and Golgi and carry proteins/lipids.
Vesicles travel to Golgi for further modifications.
Vesicles from the Golgi can have different fates, including staying in the cytoplasm or fusing with the plasma membrane.

Organelles with Double Membranes

Nucleus
Chloroplasts
Mitochondria

Mitochondria

Mitochondria have two membranes (inner & outer), with the space between them being called the intermembrane space.
Inner membrane is folded into cristae.
Contain matrix.
Responsible for ATP (energy) production.

ATP Synthesis

Mitochondria produce ATP.
ATP is a form of cellular energy.
Lack of ATP can lead to fatigue.

Study Tips

Get enough rest; lack of sleep impairs retention.
Use a calendar for organizing tasks.

Class Interaction

Encourage discussion among students.
Use games and question formats.
Award points for questions/answers.

Important Terms

Stoma and stroma (chloroplast structure)
Organelles (structures within the cells)

Cell Transport

Cells need essential materials like oxygen, water, and ions.
Mitochondria is responsible for ATP production.
Both need oxygen to make ATP.

Plasma Membrane Permeability

The plasma membrane is selectively permeable, allowing some molecules in and out.
Examples include oxygen/water entering; carbon dioxide leaving.

Selective Permeability

The plasma membrane allows some materials through.
Oxygen/water can pass through the membrane.
Glucose cannot easily pass through the membrane without help.

Passive Transport

Passive transport moves substances across the membrane without using energy.
Moves from high to low concentration.
Examples include oxygen, water, and carbon dioxide.

Active Transport

Active transport moves substances against the concentration gradient, requiring energy.
Moves from low to high concentration.
Requires ATP.

Diffusion and Osmosis

Diffusion is the movement of molecules from high to low concentration.
Osmosis is the diffusion of water across a selectively permeable membrane.