Cell Biology part 2: Membranes and Transport

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Questions and Answers

What regulates the progression of the cell cycle?

Hormones

Cyclins and cyclin dependent-kinases (correct)

Genetic mutations

Environmental factors

What is the result of meiosis in terms of genetic material?

It produces tetraploid gametes

It eliminates genetic variability

It produces diploid cells identical to the parent

It produces haploid cells with re-assorted genetic information (correct)

What characteristic do membrane lipids exhibit?

They have both hydrophilic and hydrophobic regions (correct)

They are hydrophobic only

They do not interact with water

They are capable of forming rigid structures

What factor most significantly decreases a molecule's permeability coefficient?

The size of the molecule and its charge Signup and view all the answers

What occurs during fertilization in terms of genetic composition?

A diploid cell is created with a unique genotype Signup and view all the answers

How do membrane lipids orient themselves in the plasma membrane?

Hydrophilic heads contact the aqueous environment Signup and view all the answers

What distinguishes passive transport from active transport?

Active transport moves solutes against their concentration gradient Signup and view all the answers

How do transporter proteins facilitate the movement of solutes across membranes?

They undergo conformational changes after binding the solute Signup and view all the answers

What is the role of primary active transporters in cellular processes?

They directly hydrolyze ATP to drive solute transport Signup and view all the answers

What is the primary function of membrane-bound proteins in complex organisms?

To communicate with the extracellular environment Signup and view all the answers

Which structure is essential for the function of a eukaryotic cell's nucleus?

Nuclear envelope Signup and view all the answers

What distinguishes active transport from passive transport in cellular processes?

Active transport requires ATP, while passive transport does not Signup and view all the answers

During eukaryotic cell division, which phase is primarily responsible for chromosome alignment at the cell's equator?

Metaphase Signup and view all the answers

Which of the following describes the primary role of the Golgi apparatus in a cell?

Protein modification and trafficking Signup and view all the answers

How does the structure of a plasma membrane relate to its function in cellular transport?

It is semi-permeable, regulating what enters and leaves the cell Signup and view all the answers

Which cellular structure is primarily involved in the process of mitosis?

Microtubules Signup and view all the answers

In which stage of mitosis do chromosomes align in the center of the cell?

Metaphase Signup and view all the answers

Which statement about the role of microtubules in mitosis is accurate?

They help in the movement of chromosomes Signup and view all the answers

What is the primary educational outcome related to mitosis in the context of the provided content?

Learning cell replication and division processes Signup and view all the answers

During which phase does the nuclear envelope begin to break down?

Prophase Signup and view all the answers

What is the phase characterized by the separation of sister chromatids?

Anaphase Signup and view all the answers

In which phase does the nuclear envelope start to reform?

Telophase Signup and view all the answers

Which type of cell division includes stages such as metaphase, anaphase, and telophase?

Meiosis Signup and view all the answers

What is the primary event that occurs during metaphase?

Chromosomes align at the cell equator Signup and view all the answers

What distinguishes anaphase from telophase?

Separation of chromatids Signup and view all the answers

Which phase directly precedes telophase in the process of mitosis?

Anaphase Signup and view all the answers

Which researchers contributed to the documentation of phases such as metaphase and anaphase?

Andrew S. Bajer and Rudolf Oldenbourg Signup and view all the answers

What role do membrane-bound proteins play in cellular functions?

They facilitate cell-to-cell adhesions. Signup and view all the answers

Which of the following describes a function related to immune system communication?

Identification of self vs non-self. Signup and view all the answers

How do actin cytoskeleton and adherens junctions contribute to cells?

They enhance the structure and strength of the cell. Signup and view all the answers

What is a primary function of microvilli found on epithelial cells?

Facilitate nutrient absorption. Signup and view all the answers

What aspect of cell structure relates to the durability of tissue?

Arrangement of tight junctions between cells. Signup and view all the answers

How does the shape of villi in the small intestine aid in their function?

Their shape increases surface area for absorption. Signup and view all the answers

Which of the following best describes the communication function of Purkinje cells?

They transmit signals through synaptic junctions. Signup and view all the answers

What function do membrane-bound proteins facilitate during changes in gene regulation within a cell?

They act as receptors to initiate changes. Signup and view all the answers

Study Notes

Cell Biology Review 2

Topics covered include animal systems, professional life, veterinary nursing, animal health, and veterinary professions.
Lecturer: Dr Dominic Harrison BVSc MRCVS
Role: Lecturer in Veterinary Pathology, Veterinary Investigations Officer
Contact: [email protected]

Cell Replication and Division - Mitosis

Interphase: Chromosomes duplicate, and copies remain attached. Chromosomes condense and become visible in the nucleus. Spindle forms in the cytoplasm.
Prophase: Nuclear membrane breaks apart, and spindle starts interacting with chromosomes.
Prometaphase: Nuclear membrane breakdown is complete, spindle interacts with chromosomes.
Metaphase: Copied chromosomes align in the middle of the spindle, or metaphase plate.
Anaphase: Chromosomes separate into two genetically identical groups, moving to opposite spindle ends.
Telophase: Nuclear membranes reappear around chromosome sets. Chromosomes spread out. The spindle breaks down.
Cytokinesis: Cell splits into two daughter cells, each containing the same number of chromosomes as the parent (diploid in humans - 2 copies of 23 chromosomes).

Mitosis and Meiosis

Meiosis: Involves genetic material exchange via homologous recombination. Two rounds of cell division create haploid gamete cells with reassorted genetic information.
Fertilization: The egg uniting with sperm results in a diploid cell with a unique genetic makeup (genotype).

The Plasma Membrane and Membrane Transport

The plasma membrane is a sheet-like bilayer composed of phospholipids, with hydrophilic heads facing outwards and hydrophobic tails inwards.
Cholesterol and proteins are integral components, as are sugar side chains.
Proteins include integral (intrinsic) and peripheral (extrinsic) proteins in the membrane.

Lipids Form Continuous Sheet-Like Bilayers

Lipid molecules are amphipathic, possessing both hydrophobic and hydrophilic regions.
Individual units are cylindrical, similar in cross-sectional area to the head group.
Saturated and unsaturated fatty acids make up the hydrophobic tails.

Membrane Lipids Arrange Themselves

Polar heads of membrane lipids contact the aqueous environment.
Individual units are wedge-shaped or cylindrical, depending on the ratio of head to tail size.
Micelles, bilayers, and vesicles are formed.

Why Did the Molecule Cross the Lipid Bilayer?

Permeability coefficient depends on molecule size and charge.
Small, nonpolar molecules (hydrophobic) cross easily.
Larger, charged molecules cross with the assistance of channel or transporter proteins.

Movement Across Membranes

Passive transport: Solutes moves down a concentration gradient (no energy required).
Active transport: Solutes move against a concentration gradient (energy required).
Transport types include simple diffusion, facilitated diffusion, channel-mediated, transporter-mediated, and active transport.

Passive Transport - Transporters vs Channels

Transporters: Specificity for the solute, change conformation to release solute on the other side of the membrane.
Channels: Form pores in the membrane, weakly interact with solutes (typically ions) allowing them to diffuse through the membrane.

Active Transport - Primary vs Secondary

Primary active transport: Use ATP hydrolysis to drive transport (e.g., Na+/K+ ATPase).
Secondary active transport: Use ion gradients established by primary active transport processes.

Membrane Bound Proteins

Types of proteins include integral (intrinsic) and peripheral (extrinsic) proteins.
Peripheral proteins are associated with the surface of the bilayer, while integral proteins are embedded within it.

Structural & Functional Relationships of Cells

Strength: Connections between cytoskeleton, adherens junctions, and cell interactions.
Durability: Relationships in cell layers related to barriers and structural integrity.
Absorption: Structural features of epithelial cells facilitating absorption.
Communication: Relationships between cells for intercellular signaling.

Summary

Eukaryotic cell structure and function were reviewed.
Cell division and coordination were discussed.
Cell membrane structure and regulation were analyzed, including a contrast between active and passive transport.
Relationships between cell structure and function were examined for various cell types.

Learning Objectives

Cell structure: Components of the cell, cytoplasm, and nucleus.
Cell division: Process and regulation of eukaryotic cell division.
Cell membrane: Structure, function, and transport mechanisms through the membrane.
Structural-functional relationships: Relationships of different cell types.

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Description

Test your understanding of key concepts in cell biology, focusing on cell cycle regulation, membrane structure, and transport mechanisms. This quiz covers essential topics including meiosis, active and passive transport, and the roles of proteins in cellular processes.