Cell Structure and Function Quiz

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.

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.