Cell Biology Lecture 2

Question 1

The Cytoplasm Overview

Definition, Components

Answer 1

Definition: The region between the plasma membrane and nucleus.
Components: Cytosol and Organelles.

Question 2

Cytosol

Definition, Composition, Function

Answer 2

Definition: Fluid portion of cytoplasm.
Composition: 55% of cell volume, mainly water (70%-90%), and dissolved solutes.
Function: Major site for chemical reactions in the cell.

Question 3

Organelles

Definition, Function

Answer 3

Definition: Specialized structures, often termed “little organs.”
Function: Contribute to overall cellular functioning and metabolic processes

Question 4

Cytoskeleton Overview

Definition, Types

Answer 4

Definition: Cellular components determining cell shape and structure.
Types: Microfilaments, Intermediate Filaments, Microtubules.

Question 5

Microfilaments

Definition, Composition, Functions

Answer 5

Definition: Smallest cytoskeleton structures.
Composition: Primarily actin protein.
Functions: Movement, support, cytokinesis, muscle contraction, anchor to cell membrane, microvilli formation.

Question 6

Intermediate Filaments

Defintion, Functions

Answer 6

Definition: Medium-sized structures made of various proteins, including keratin.
Functions: Internal stability, organelle positioning, cell junction support.

Question 7

Microtubules

Definition, Structure, Functions

Answer 7

Definition: Largest cytoskeleton structures mainly composed of tubulin protein.
Structure: Long, hollow tubes produced in the centrosome.
Functions: Determine cell shape, facilitate organelle and chromosome movement, form external structures like cilia and flagellum.

Question 8

Centrosome

Definition, Components, Functions

Answer 8

Definition: Microtubule organizing center.
Components: Centrioles (cylindrical structures), pericentriolar material.
Functions: Involved in mitosis/meiosis, starting point for mitotic spindles.

Question 9

Cilia

Definition, Functions

Answer 9

Definition: Hair-like projections for cell mobility.
Functions: Coordination in movement (e.g., egg cells), sweeping foreign particles (e.g., respiratory tract).

Question 10

Flagella

Definition, Location

Answer 10

Definition: Long, whip-like structures for cell propulsion.
Location: Found in sperm cells.

Question 11

Ribosomes

Definition, Location, Composition

Answer 11

Definition: Responsible for protein synthesis (translation).
Location: Free-floating (cytosol) or attached to endoplasmic reticulum.
Composition: 2 subunits of ribosomal RNA (rRNA).

Question 12

Endoplasmic Reticulum (ER)

Definition, Types

Answer 12

Definition: Network of tubules or sacs extending from the nuclear membrane.
Types: Smooth ER (lipid production, detoxification), Rough ER (ribosomes, protein synthesis).

Question 13

Golgi Complex/Apparatus/Body (GB)

Functions, Structure

Answer 13

Functions: Receives, transports, and modifies proteins from rough ER.
Structure: Three sacs - entry/cis face, medial cisternae, exit/trans face.

Question 14

Vesicles

Definition, Examples

Answer 14

Definition: Compartments formed by lipid bilayer.
Examples: Lysosomes (digestive enzymes), Peroxisomes (digestive proteins, detoxification), Secretory Vesicles (transport materials for exocytosis).

Question 15

Mitochondria

Definition, Structure, Unique Features

Answer 15

Definition: Powerhouse of the cell, generates ATP through aerobic metabolism.
Structure: Outer and inner membrane, cristae folds in the matrix.
Unique Features: Self-replicating, contains own DNA (maternal inheritance).

Question 16

Nucleus

Definition, Structure, Components

Answer 16

Definition: The brain of the cell, responsible for genetics and protein synthesis.
Structure: Double membrane (nuclear envelope) with pores.
Components: Nucleolus (makes rRNA), Genetic Material (DNA, genes, chromosomes).

Question 17

DNA Structure

Description, Components, Bonding

Answer 17

Description: Double-stranded helix.
Components: Alternating pentose sugars and phosphate group.
Bonding: Complementary nitrogenous base pairs form hydrogen bonds.

Question 18

DNA Length

Insight, Fact

Answer 18

Insight: Stretched DNA in one cell = 6 feet.
Fact: Stretched DNA in the human body = 108 billion km (equal to 150,000 round trips to the Moon).

Question 19

Genes

Definition, Purpose, Quantity

Answer 19

Definition: Segments of DNA encoding specific traits.
Purpose: Code for proteins influencing structure, function, appearance.
Quantity: Approximately 20,000 genes in the human genome.

Question 20

Alleles

Explanation, Examples, Genetic Makeup, Observable Traits

Answer 20

Explanation: Normal DNA sequence variation at a genomic location.
Examples: Alleles for hair color (red, blonde, brown).
Genetic Makeup: Genotype (base pair sequence).
Observable Traits: Phenotype.

Question 21

Histones and Nucleosomes

Definitions + Linker DNA

Answer 21

Histones: Protein balls around which DNA double helix coils.
Nucleosomes: Combination of histones and clusters of double-stranded DNA.
Linker DNA: Section linking nucleosomes together.

Question 22

Chromatin

Definition, State

Answer 22

Definition: DNA, RNA, & proteins scattered before cell division.
State: Appears diffuse and granular, clusters to form chromosomes during division.

Question 23

Chromosomes and Chromatids

Chromosomes, Homologous Chromosomes, Chromatids, Centromere

Answer 23

Chromosomes: Arrangement of chromatin fibers during cell division.
Homologous Chromosomes: Form pairs (1-22 autosomal, 23 sex chromosomes).
Chromatids: Half of a chromosome; 1 pair = 1 chromosome.
Centromere: Central portion holding chromatids or sister chromatids together.

Question 24

Telomeres

Description, Function, Consequence

Answer 24

Description: Non-coding, repeated units at chromosome ends.
Function: Protect ends, prevent loss during cell division.
Consequence: Shorter telomeres associated with diseases, poor survival, aging.

Question 25

Genome

Definition, HGP, Progress

Answer 25

Definition: Total genetic information in the nucleus.
Human Genome Project (HGP): Completed in 2003, mapped much of the genome.
Progress: In 2022, genome almost completely mapped.

Question 26

Genome and Intelligence

Insight, Example

Answer 26

Insight: Number of genes does not correlate with intelligence.
Example: Some plants have more genes than humans, challenging traditional assumptions.