Chapter 4 - Cells

Question 1

What are the 4 overlapping stages that are hypothesized to have led to the origin of living cells?

Answer 1

1) Nucleotides and amino acids were produced first in a prebiotic soup
2) Polymers formed (RNA and/or DNA, proteins)
3) Polymers became enclosed in membranes (Protobionts)
4) Polymers enclosed in membranes acquired the properties of living cells

Question 2

What is the Reducing atmosphere hypothesis?

Answer 2

The early earth atmosphere facilitated reactions to form organic molecules

Question 3

What is the deep-sea vent hypothesis?

Answer 3

Key organic molecules originated from deep-sea vents where dissolved gases and metal ions mixed with cold sea water

Question 4

What is the extraterrestrial hypothesis?

Answer 4

Organic molecules were carried to earth in meteorites

Question 5

What is the RNA world and how could it have evolved into a DNA/RNA/protein world?

Answer 5

• It is a hypothetical period on early earth where RNA delivered the functions of both DNA and RNA.
• Incorporation of DNA may have allowed RNA to take on other roles and DNA is more stable than RNA

Question 6

What are some similarities between living cells and protobionts? (hint: there are 3)

Answer 6

• Information-containing polymers
• Ability to divide and increase in number
• Boundry which separates internal and external environments

Question 7

What are some differences between living cells and protobionts?

Answer 7

Protobionts: Use prebiotically created monomers
Living cells: Undergoes controlled precise self-replication

Question 8

Definition of resolution in microscopy.

Answer 8

The measure of the clarity of an image

Question 9

Definition of contrast in microscopy.

Answer 9

Relative differences in lightness, darkness, or color

Question 10

Definition of magnification in microscopy.

Answer 10

The ratio between the size of an image produced by a microscope and the object’s actual size

Question 11

What is the difference between a light microscope and an electron microscope?

Answer 11

What they use for illumination (Light microscope-use light and Electron microscope-use electrons)

Question 12

What are the 4 factors that determine cell structure and function?

Answer 12

Matter, Energy, Organization, and Information

Question 13

True or false: Prokaryotes contain a plasma membrane, internal membrane-bound organelles, a cell wall, and ribosomes.

Answer 13

False: Prokaryotes do not have internal membrane-bound organelles

Question 14

What are some differences between the general structure of prokaryotic and eukaryotic cells?

Answer 14

Prokaryotic cells do not have a nucleus and Eukaryotic cells are compartmentalized by internal membranes to create organelles

Question 15

Explain how the proteome underlies the structure and function of cells.

Answer 15

The DNA in different cells is identical, but the cells have different proteomes, and structure is what determines function

Question 16

How does cell size and shape affect the ratio between surface area and volume?

Answer 16

Internal cell volume and membrane surface area change differently as the radius of the cell increases

Question 17

Where is cytosol located in a eukaryotic cell and what’s it general function?

Answer 17

• It is outside the cell organelles but inside the plasma membrane
• It is a fluid necessary for biochemical reactions

Question 18

Describe the three types of protein filaments that make up the cytoskeleton.

Answer 18

Microtubules–Long, hollow, cylindrical structures composed of protein subunits
Intermediate filaments–Built from several types of proteins
Actin filaments–thinnest filament made of actin subunits; two strands spiral around each other

Question 19

Describe the functions of the three types of protein filaments.

Answer 19

Microtubules–cell shape and organization
Intermediate filaments–cell shape and rigidity
Actin filaments–cell shape and strength

Question 20

How do motor proteins interact with microtubules or actin filaments to promote cellular movement?

Answer 20

Motor proteins and filaments are fixed in place, so the actions of the motor proteins cause the microtubules to bend

Question 21

What are some similarities between cilia and flagella?

Answer 21

• Cell appendages that bend to produce different types of cell movement
• Same internal structure (Axoneme)

Question 22

What are some differences between cilia and flagella?

Answer 22

• Flagella is usually longer than cilia and are either found in pairs or single
• Cilia are numerous and tend to cover all or part of the cell surface

Question 23

Describe the structure and organization of the cell nucleus

Answer 23

• Composed of DNA and proteins (chromatin)
• Contains a nuclear matrix which organizes chromosomes

Question 24

Where are Ribosomes usually assembled in?

Answer 24

The Nucleolus

Question 25

Outline the structure and general function of the nuclear envelope.

Answer 25

A double membrane structure that houses genetic material

Question 26

Outline the structure and general function of the plasma membrane.

Answer 26

Controls movement of substances into and out of the cell (the site of cell signaling) Three important functions: Membrane transport, cell signaling, and cell adhesion

Question 27

Outline the structure and general function of the Endoplasmic Reticulum.

Answer 27

Network of membranes that initiate the sorting of some proteins and carries out metabolic functions

Question 28

What are the main differences between Rough ER and Smooth ER?

Answer 28

Rough ER--protein synthesis + studded with ribosomes Smooth ER--lipid synthesis + detoxification

Question 29

Outline the structure and general function of the Golgi Apparatus.

Answer 29

Site of modification, sorting, and secretion of lipids and proteins

Question 30

Outline the structure and general function of Lysosomes.

Answer 30

Site where macromolecules are degraded

Question 31

Outline the structure and general function of Vacuoles.

Answer 31

A vesicle within the cytoplasm enclosed by a membrane and regulates water + nutrients and in charge of waste disposal

Question 32

Outline the structure and general function of Peroxisomes.

Answer 32

Catalyze certain reactions and break down molecules by removing hydrogen and adding oxygen (usually found in the Liver)

Question 33

Outline the structures and general functions of mitochondria and chloroplasts

Answer 33

- Grow and divide to reproduce themselves - Aren't completely autonomous because they depend on the cell for synthesis of internal components - Mitochondria's primary role is making ATP while Chloroplasts is used for photosynthesis

Question 34

Define the endosymbiosis theory.

Answer 34

The Mitochondria and Chloroplasts originated from prokaryotic cells which were then engulfed by eukaryotic cells.

Question 35

List the categories of proteins sorted in Cotranslational sorting.

Answer 35

Proteins destined for the ER, Golgi, Lysosomes, Vacuoles, Plasma Membrane, and secreted proteins

Question 36

List the categories of proteins sorted in post-translational sorting.

Answer 36

Proteins for the Nucleus, Mitochondria, Chloroplasts, and Peroxisomes

Question 37

What are the functional roles of the Extracellular matrix (ECM) in animals?

Answer 37

Provides structural and biochemical support to the surrounding cells

Question 38

Describe the major structural components of the ECM of animals.

Answer 38

The ECM is mostly composed of fibrous proteins and polysaccharides

Question 39

Describe the structure and function of plant cell walls.

Answer 39

- Cellulose and other polysaccharides make up the cell wall - Usually thicker, stronger, and more rigid than ECM - Primary cell wall (flexible for cells can grow) - Secondary cell wall (deposited between the membrane and primary)

Question 40

What is the difference between bacterial cells and eukaryotic cells?

Answer 40

- Bacterial cells are relatively simple - Eukaryotic cells are a system of four interacting parts (nucleus, cytosol, endomembrane system, and semiautonomous organelles)

Question 41

Which ECM component attracts water and resists compression, giving the ECM a gel-like character?

Answer 41

Glycosaminoglycans (A polysaccharide)