Chapter 2: Cellular Level of Organization

BIOL- Anatomy

What do humans and amoebas have in common?

made of cells, plasma membrane, functional and structural similarities

What are the 3 parts of the cell theory?

all living things are cells, cells are the smallest unit of life, all cells come from other cells

what are two parts of a phospholipid?

hydrophilic head, hydrophobic tail

Why do phospholipids form a bilayer?

Hydrophilic heads face the watery environments while hydrophobic tails face inward away from water.

How do small nonpolar molecules and gases cross the membrane?

They diffuse directly through the phospholipid bilayer.

How do ions and many water-soluble molecules cross the membrane?

Through membrane proteins such as channels or transporters.

How do very large molecules enter or leave a cell?

Through vesicles using endocytosis or exocytosis.

What is the difference between endocytosis and exocytosis?

Endocytosis brings materials into the cell; exocytosis moves materials out.

What is the main function of rough ER?

Makes and processes proteins

What is the main function of smooth ER?

Makes lipids and performs other cellular functions

Why is the Golgi apparatus called the "post office" of the cell?

It modifies, sorts, and packages molecules for delivery to their destinations

How are lysosomes formed?

The ER makes digestive enzymes and the Golgi modifies and packages them into lysosomes.

What is the function of mitochondria?

Produce ATP through cellular respiration.

Why is the inner mitochondrial membrane folded?

The folds increase surface area for ATP-producing reactions.

What is the function of the nucleus?

Stores DNA and controls gene expression.

What is transcription?

Making an RNA copy of DNA.

What is the function of ribosomes?

Build proteins.

What is translation?

Using mRNA instructions to build a protein.

What are the two major categories of cell junctions?

Anchoring junctions and communicating junctions.

What do anchoring junctions do? Give an example.

They hold cells together and provide strength; an example is a desmosome.

What do communicating junctions do? Give an example.

They allow cells to communicate with each other; an example is a gap junction.

How does an adipocyte's structure help its function?

Its large lipid droplet allows it to store energy.

How does a sperm cell's structure help its function?

Its flagellum allows it to swim toward the egg.

How does a neuron’s structure help its function?

Its long extensions allow it to send signals over long distances.

How does a red blood cell's structure help its function?

Its biconcave shape increases surface area for gas exchange, and it lacks a nucleus to provide more room for hemoglobin.

How does an intestinal cell's structure help its function?

Microvilli increase surface area for nutrient absorption.

How does a muscle cell's structure help its function?

Specialized contractile proteins allow it to shorten and produce force.

How does an oocyte's structure help its function?

Its large size and abundant cytoplasm provide materials needed for early development.

What happens during interphase?

The cell grows, performs normal functions, copies its DNA, and prepares for division.

What happens during the stages of mitosis?

Prophase: chromosomes condense → Prometaphase: nuclear envelope breaks down and spindle fibers attach → Metaphase: chromosomes line up → Anaphase: sister chromatids separate → Telophase: new nuclei form.

What is cytokinesis?

Division of the cytoplasm to form two daughter cells.

What are sister chromatids?

Identical copies of a chromosome that were produced during DNA replication.

What do spindle fibers do?

Attach to chromosomes and help separate sister chromatids during mitosis.

How does cancer relate to cell division?

Cancer can occur when cells lose normal control of cell division and divide uncontrollably.