Chapter 7 - Cell Structure and Function

Question 1

Surface area to volume ratio

Answer 1

inversely proportional

-the smaller the volume of a cell, the larger the surface area to volume ratio

Question 2

Examples of cells that have exceptional dimensions

Answer 2

1) Nerve cell
- glial cells support and nourish them
2) Muscle cell
- has transverse tubule (T-tubule)

Question 3

Sedimentation order by weight (differential centrifugation) of plant cells

Answer 3

Central vacuole => Nucleus => Chloroplast => Mitochondria => Endomembrane System => Plasma membrane => Ribosome

Question 4

Sedimentation order by weight (differential centrifugation) of animal cells

Answer 4

Nucleus => Mitochondria => Endomembrane system => Plasma membrane => Ribosome

Question 5

Genetic material of prokaryotic cells

Answer 5

Bacterial chromosome
-major genetic information

Plasmid
-accessory genetic information

Question 6

Prokaryotic capsule

Answer 6

• jelly-like
• composed of polysaccharides to avoid host cell’s immune response
  e. g. smooth and rough type - smooth are pathogenic as they are difficult to detect

Question 7

Mesosome

Answer 7

• infoldings/invagination of the plasma membrane in bacteria

- role: DNA replication, cell division, excretion

Question 8

Eukaryotic chromatin

Answer 8

30nm fiber

Question 9

Nuclear lamina

Answer 9

• cytoskeleton with net-like array on the inner membrane
• made of intermediate filament (Structural support)
• damage causes progeria (extreme aging in children)

Question 10

Plant vs. animal cells

Answer 10

Plant

• cell membrane + cell wall
• organelles of chloroplast and central vacuole

Animal

• only cell membrane
• organelles of lysosomes and centrioles are present

Question 11

Double membrane organelles

Answer 11

1) Nucleus
2) MItochondria
3) Chloroplast

Question 12

Nucleolus

Answer 12

• densely stained region within the nucleus
• non-membranous organelle
• role: ribosomal assembly

Question 13

Ribosome

Answer 13

• made of rRNA + proteins
• has large and small subunit
• free or membrane-bound

Question 14

Bound ribosome

Answer 14

• attached to rER
• produces secretary proteins (digestive enzymes, hormones)
• chemical modification off proteins (glycosylation)

Question 15

Free ribosome

Answer 15

• freely floating in cytoplasm

- synthesizes cytoplasmic proteins (e.g. enzymes)

Question 16

Endomembrane system

Answer 16

• extensive network of membranous organelles
• includes: nuclear envelope, endoplasmic reticulum (rER, see), Golgi apparatus, lysosome, vesicles, plasma membrane
• role: translocation and modification of molecules (nucleic acid, carbs, proteins, lipids) in and out of cells

Question 17

Transitional ER

Answer 17

• end of smooth & rough ER

- exit site of proteins leaving the ER => go to Golgi apparatus for modification and packaging

Question 18

Rough ER

Answer 18

• single membrane, has bound ribosomes

- role: produce and modify secretory protein

Question 19

Smooth ER

Answer 19

-single membrane, no ribosomes
-role:
lipid biosynthesis (steroid, triacylglycerol)
chemical modification of secretory protein
Ca2+ storage in muscle cell
Detoxification of toxic materials and drugs

Question 20

Golgi apparatus

Answer 20

• stacks of cisternae (flattened sacs)
• role: post office - receive proteins on cis side and sort/ship them through trans side, produces lysosome , polysaccharide biosynthesis

Question 21

Types of vacuoles

Answer 21

1) Central vacuole
- storage of waste materials (trash can)
2) Food vacuole
- produced by phagocytosis of WBC
- fuses with lysosome for food hydrolysis
3) Contractile vacuole
- regulates osmolarity in paramecium

Question 22

Peroxisome

Answer 22

• membrane-bound organelle

- role: catabolism of long chain fatty acids and detoxify hazardous byproducts (hydrogen peroxide)

Question 23

Glyoxysomes

Answer 23

specialized peroxisome in plant seeds

-stores fat and lipid germination

Question 24

Types of cytoskeleton

Answer 24

1) Microtubule (thickets)
2) Intermediate filament
3) Microfilament (thinnest)

Question 25

Microtubule

Answer 25

- thickest (25nm) - hollow tube - composed of tubule (dimer of alpha- and beta- tubule monomers) Role - maintenance of cell shape - motility example: 1) centrosome - non-motile microtubule (9+0) 2) cilia - motile microtubule (9+2), trachea 3) flagella - motile microtubule (9+2), sperm

Question 26

Intermediate filaments

Answer 26

- middle size (10nm) - fibrous proteins coiled into cable - found in laminae and keratin (hair) Role: - maintenance of cell shape - anchorage of nucleus

Question 27

Microfilaments

Answer 27

- thinnest (7nm) - two intertwined strands of actin Role: - ameboid movement - crawling found in pseudopodia of phagocytosis - cytoplasmic streaming in plant cells (circulation) - structural support of microvilli - cleavage furrow in animal cell

Question 28

Animal cell's extracellular matrix (ECM)

Answer 28

1) Proteoglycan 2) Collagen 3) Fibronectin 4) Integrin

Question 29

3 types of cell junction

Answer 29

1) tight junction 2) desmosome 3) gap junction