Midterm 1: Lec 3 Slides

Question 1

What is the largest organelle?

Answer 1

Nucleus

Question 2

What is the nuclear envelope’s structure?

Answer 2

2 membranes perforated by nuclear pores

Question 3

What is chromatin?

Answer 3

DNA combined with protein; “uncondensed” or uncoiled chromosomes

Question 4

What does each chromosome contain?

Answer 4

One long molecule of DNA, comprising many genes

Question 5

What happens at the nucleolus?

Answer 5

Ribosome assembly; cell may have more than one

Question 6

Nucleoplasm

Answer 6

Fluid material within the nuclear envelope

Question 7

Nuclear lamina

Answer 7

Network of proteins (lamins) which maintains the nucleus’s shape

Question 8

When do chromosomes form the X shape?

Answer 8

Just prior to cell division

Question 9

Where are ribosomes located?

Answer 9

Floating in cytoplasm, attacked to rough ER, or in energy-producing organelles (mitochondrial matrix, chloroplast stroma)

Question 10

Ribosomal structure

Answer 10

Type of RNA with protein; has small subunit and large subunit

Question 11

Endomembrane system (what is it and what’s in it)

Answer 11

Series of interrelated membranes and compartments in eukaryotic cells; comprises endoplasmic reticulum and Golgi apparatus (“endogolgi reticulatus”)

Question 12

Why would cells have more ER?

Answer 12

They synthesizes proteins for export

Question 13

What takes place in the smooth ER?

Answer 13

Hydrolysis of glycogen and steroid synthesis

Question 14

Smooth vs. Rough ER - what’s the difference?

Answer 14

No ribosomes vs. yes ribosomes

Question 15

What takes place in the rough ER?

Answer 15

Manufacture of proteins for export/incorporation into membranes/movement into endomembrane system organelles; also addition of short sugar chains to proteins

Question 16

Regions of the Golgi apparatus

Answer 16

Cis region: closest to nucleus

Trans region: closer to cell surface

Question 17

What happens in Golgi?

Answer 17

Modification, packaging, and sorting of proteins; synthesis of some polysaccharides for cell wall

Question 18

Describe vesicle movement as related to the Golgi

Answer 18

Vesicles from rough ER fuse with cis region, and secretory vesicles are pinched off of trans region

Question 19

What do signal sequences do in proteins?

Answer 19

Direct them to their cellular destinations

Question 20

What signal sequence directs polypeptide chain to the ER?

Answer 20

Hydrophobic sequence of ~25 amino acids at the beginning of the polypeptide chain

Question 21

Mitochondria function (specific, not just powerhouse of the cell)

Answer 21

Convert energy from food into ATP (energy currency of cell)

Question 22

Mitochondria structure

Answer 22

Inner and outer membrane; inner membrane folds to form cristae

Question 23

What is in the mitochondrial matrix?

Answer 23

Ribosomes and DNA

Question 24

What does it mean if a cell has more mitochondria?

Answer 24

It is very active (e.g., heart muscle)

Question 25

What is the size of mitochondria?

Answer 25

Small, similar in size to many bacteria

Question 26

What is the function of plastids and where are they found? Give an example of a plastid.

Answer 26

- Present in plants and some protists - Manufactures or stores food - Example is chloroplast

Question 27

Chloroplast structure

Answer 27

Surrounded by 2 unfolded membranes; inner membrane forms thylakoids (stack of flattened disk-like sacs)

Question 28

What are stacks of thylakoids called?

Answer 28

Grana

Question 29

Where is chlorophyll found?

Answer 29

Thylakoid membrane

Question 30

What is in the stroma fluid and where is it?

Answer 30

- Located in inner membrane of chloroplast | - Contains suspended grana, ribosomes and DNA

Question 31

Endosymbiotic theory

Answer 31

Larger prokaryotes engulfed smaller prokaryotes (aka mitochondria and chloroplasts)

Question 32

Lysosome function

Answer 32

Participate in phagocytosis and contain hydrolytic digestive enzymes ("suicide bags")

Question 33

What replaces lysosomes in plant cells?

Answer 33

Large vacuoles (perform same role)

Question 34

Peroxisome function (and found where?)

Answer 34

Use oxygen to carry out metabolic reactions like creation of hydrogen peroxide; uses other enzymes to break down molecules like H2O2; also functions in lipid breakdown -found in plant and animal cells

Question 35

Glyoxysome function (and found where?)

Answer 35

Break down lipids in plant cells (only found in plant cells)

Question 36

Vacuole function (and found where?)

Answer 36

Store waste products and provide turgor (keeps plants rigid); only in plant cells

Question 37

Components of primary lysosome (4) and functions?

Answer 37

Proteases (break down proteins), lipases (break down lipids), nucleases (break down nucleic acids), carbohydrate-digesting enzymes

Question 38

How does the interior pH of lysosomes compare to the cell?

Answer 38

It's acidic (pH 5.5) compared to pH 7 of normal cell - why compartmentalization is good

Question 39

What lysosome problem is central to Tay Sachs disease?

Answer 39

Inability to break down gangliosides, a type of lipid

Question 40

Autophagy

Answer 40

Breakdown of worn-out cell organelles

Question 41

Cytoskeleton function

Answer 41

Maintain cell shape, facilitate cell movement, and certain fibers are "motor protein" tracks

Question 42

Cell wall - which cells have it?

Answer 42

Plants, fungi, bacteria, and some protists

Question 43

Extracellular matrix location and composition

Answer 43

Surrounds animal cells; composed of proteins (collagen, glycoproteins, proteoglycan)

Question 44

Cytoskeleton components

Answer 44

Microfilaments, intermediate filaments, microtubules

Question 45

What are microfilaments and what do they do?

Answer 45

Strands of actin; involved in movement during animal cell division, and muscle contraction

Question 46

What are intermediate filaments and what do they do?

Answer 46

Tough, fibrous protein molecules twisted into rope-like structures - stabilize cell structure (e.g., keratin)

Question 47

What are microtubules and what do they do?

Answer 47

Hollow cylinders composed of tubulin; involved in structure and function of cilia and flagella, centrioles, and organelle movement - important in mitotic spindle

Question 48

What do dynein and kinesin (motor proteins) do?

Answer 48

Use energy from ATP to change their shape and move things

Question 49

What structures are unique to plant cells?

Answer 49

Cell wall, chloroplasts, vacuoles (animal cells may have small ones)

Question 50

What structures are unique to animal cells?

Answer 50

Flagella, centrioles, extracellular matrix (plant cells may have it)