Cell Structure and Function Quiz

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Questions and Answers

What is the primary function of the rough endoplasmic reticulum?

Storage of calcium for muscle contraction

Synthesis of lipids

Protein synthesis due to attached ribosomes (correct)

Modification and packaging of proteins

What role do lysosomes play in the cell?

Storage of calcium ions

Intracellular digestion of macromolecules (correct)

Synthesis of ribosomal subunits

Modification and distribution of proteins

How do secretory vesicles operate within the cell?

They transport materials from the Golgi apparatus to the plasma membrane (correct)

They digest worn-out organelles

They assist in protein synthesis

They store calcium for muscle function

What defines the primary active transport process?

Movement of substances against a concentration gradient requiring energy Signup and view all the answers

What is the main function of the Golgi apparatus?

Modification and distribution of proteins and lipids Signup and view all the answers

What type of molecules primarily comprise the plasma membrane?

Lipids and proteins Signup and view all the answers

Which structure is responsible for the synthesis of ribosomal subunits?

Nucleolus Signup and view all the answers

What is the primary role of channel proteins in facilitated diffusion?

Carrying ions or molecules across the membrane along a concentration gradient Signup and view all the answers

Which component is responsible for the lipid bilayer's stability in the plasma membrane?

Cholesterol Signup and view all the answers

Which part of the cytoskeleton is primarily involved in cell division and intracellular transport?

Microtubules Signup and view all the answers

What is the role of peripheral proteins in the plasma membrane?

Attach to the bilayer but do not penetrate it Signup and view all the answers

What distinguishes secondary active transport from primary active transport?

It relies on the concentration gradient established by primary active transport. Signup and view all the answers

How does osmosis differ from simple diffusion?

It exclusively refers to the movement of water across a semipermeable membrane. Signup and view all the answers

What is the primary function of peroxisomes in the cell?

Break down fatty acids. Signup and view all the answers

Which organelle is responsible for the majority of ATP production in the cell?

Mitochondria Signup and view all the answers

What role do centrioles play during cell division?

They form spindle fibers. Signup and view all the answers

What is a distinguishing feature of mitochondria?

They contain their own DNA. Signup and view all the answers

Which structure aids in the movement of small particles across the cell surface?

Cilia Signup and view all the answers

What happens to the cell's chromatin during mitosis?

It becomes densely coiled into chromosomes. Signup and view all the answers

Which phase of the cell cycle is characterized by DNA replication?

S phase Signup and view all the answers

What event marks the beginning of cytokinesis?

Formation of cleavage furrow Signup and view all the answers

What is apoptosis?

A process of programmed cell death. Signup and view all the answers

How do microvilli enhance cellular function?

By increasing the surface area for absorption. Signup and view all the answers

What type of structure do flagella provide to examples like sperm cells?

Movement for the entire cell. Signup and view all the answers

What is the main purpose of proteasomes?

To break down and recycle proteins. Signup and view all the answers

Which phase comes after mitosis in the cell cycle?

Cytokinesis Signup and view all the answers

What is the role of catalase in peroxisomes?

To break down hydrogen peroxide. Signup and view all the answers

Study Notes

Cell Overview

Cells are the fundamental unit of life, present in all living organisms, including humans.

Functions of Cell

Cell Metabolism and Energy Use: Encompasses all chemical reactions within the cell that involve energy transformations.
Synthesis of Molecules: Cells synthesize proteins, nucleic acids, and lipids.
Communication: Cells use chemical and electrical signals to interact with each other.
Reproduction and Inheritance: Cells contain the complete genetic information and divide to propagate this information as organisms grow.

Plasma Membrane

Structure: The outermost boundary of the cell, composed of lipids (50%) and proteins (45-50%) with minimal carbohydrates (4-8%).
Functions: Acts as a boundary, supports cell contents, facilitates cell attachment, and controls substance movement in/out of the cell.
Membrane Potential: Describes the electrical charge difference across the membrane, with positive ions outside and negative ions inside.
Fluid-Mosaic Model: Indicates that the plasma membrane is flexible and changes shape over time, allowing proteins to move within the lipid bilayer.

Movement Across the Plasma Membrane

Diffusion: Movement of solutes from high to low concentration until equilibrium is reached, influenced by concentration difference, temperature, size of particles, and solvent viscosity.
Osmosis: Diffusion of water across a semipermeable membrane; three terms describe osmotic pressure: isosmotic, hyperosmotic, and hyposmotic.
Facilitated Diffusion: Mediated by carrier and channel proteins, allowing substances to move from higher to lower concentration.
Primary Active Transport: Uses ATP to move substances against concentration gradients (e.g., Na-K ATPase pump).
Secondary Active Transport: Uses established gradients to move different ions or molecules (e.g., Sodium-Glucose Transporter).

Cytoplasm

Cytoplasm: The material within the plasma membrane excluding the nucleus, consisting of cytosol and organelles.
Cytosol: Viscous fluid containing ions, molecules, and enzymes for metabolism.
Cytoskeleton: Provides structural support and is involved in cell movement and shape changes, comprising three protein groups: microtubules, actin filaments, and intermediate filaments.
Cytoplasmic Inclusions: Aggregates of substances within the cytoplasm, such as lipid droplets and glycogen granules.

Nucleus

A large membrane-bound structure containing nucleoplasm and nuclear pores, where DNA and RNA synthesis occurs.
Nucleolus: A dense area within the nucleus responsible for ribosome subunit production.

Ribosomes

Sites of protein synthesis, consisting of large and small subunits, found free in cytoplasm or attached to the endoplasmic reticulum.

Endoplasmic Reticulum

A network of membranes connected to the nuclear envelope, with rough ER (site of protein synthesis due to ribosomes) and smooth ER (lipid synthesis and detoxification).

Golgi Apparatus

Series of stacked membranous sacs that modify, package, and distribute proteins and lipids received from the endoplasmic reticulum.

Vesicles

Secretory Vesicles: Pinch off from the Golgi apparatus and release contents through exocytosis, with their membranes incorporated into the plasma membrane.
Lysosomes: Contain hydrolytic enzymes for digestion of various biomolecules.
Peroxisomes: Smaller than lysosomes, involved in breaking down fatty acids and detoxifying substances.
Proteasomes: Complexes that degrade and recycle proteins within the cell.

Mitochondria

Organelles that produce ATP through aerobic respiration, containing inner and outer membranes with cristae and a matrix.

Cell Division

This process encompasses interphase, which is divided into the G1 phase (cell growth and preparation for DNA replication), S phase (DNA synthesis), and G2 phase (final preparations for mitosis), followed by cell division, which consists of mitosis (nuclear division) and cytokinesis (cytoplasmic division).
Mitosis: Mitosis is a critical process of cellular division where the genetic material within the cell’s nucleus is duplicated and evenly distributed into two daughter nuclei. This process is essential for growth, tissue repair, and asexual reproduction in organisms.
Cytokinesis: This crucial biological process occurs at the end of mitosis, specifically initiated during the late stages of anaphase. It involves the physical separation of the cytoplasm and organelles, ultimately resulting in the formation of two distinct daughter cells, each containing identical genetic material.

Apoptosis

This programmed cell death regulates cell numbers and is controlled by genes coding for apoptotic proteins, leading to cell fragmentation and removal by macrophages.

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Description

This quiz covers the fundamental concepts of cell structure and function, emphasizing the roles of metabolism, communication, and molecule synthesis within cells. Test your knowledge on how cells operate and interact with their environment.