Cell Structure And Function

Question 1

___ Molecules need transporter to move from outside to inside of cell. Why?

Answer 1

Water soluble because the inner part of the phospholipid bilayer is hydrophobic

Question 2

___ transport molecules across cell membrane; what do they look like

Answer 2

Integral proteins; span the entire phospholipid bilayer

Question 3

What happens in the nucleus? (3 things)

Answer 3

Location of DNA and chromatin, DNA replication, and transcription to mRNA

Question 4

What happens in nucleolus?

Answer 4

Synthesis of rRNA

Question 5

Function of mitochondria?

Answer 5

Generates ATP and synthesizes steroids

Question 6

Function of rough and smooth ER

Answer 6

Rough - translates mRNA to peptide (protein) on its ribosomes to be secreted or inserted into cell membrane

Smooth- detoxification and metabolizes lipids, steroids, and glycogen

Question 7

Golgi body function? What is derived from golgi?

Answer 7

Packages translated proteins from rER

Secretory granules which are vesicles involved in secretion (exocytosis)

Question 8

Lysosomes?

Answer 8

Degrade material

Question 9

Centrioles synthesize ___?

Two main functions of this?

Answer 9

Microtubules

1. Transport
2. Modified cell shape (major part of cytoskeleton)

Question 10

Nuclear envelope is continuous with?
Which has spaces called?
Which control?

Answer 10

RER
Nuclear pores
What goes into and out of the nucleus

Question 11

Things travel through the nuclear pore complex to get into and out of the nucleus

1. Types of things that go into the nucleus?
2. Out of the nucleus?

Answer 11

1. Enzymes and other proteins made in the cytoplasm

2. mRNA and ribosomes made in the nucleus

Question 12

Function of the importin and exportin protein

Answer 12

Enables transport by a carrier protein (to get larger molecules into/out of nuclear pore)

Question 13

After dna transcribes to mRNA, where is the mRNA exported?

Answer 13

Ribosomes in cytoplasm or on rough ER for translation into proteins

Question 14

Job of nucleolus

Answer 14

Makes rRNA and then assembles rRNA and ribosomal proteins into ribosomes

Question 15

What does “beads on a string” refer to?

Answer 15

(Slide 23 diagram)

Chromatin fibrils which occurs when dna is wound around histones (which are large proteins)

Question 16

Euchromatin and heterochromatin similarity and difference

Answer 16

Both are formed when chromatin fibrils coil

Euchromatin = loosely coiled (state when cell is not dividing)

Heterochromatin = tightly coiled (preparing for cell division)

Question 17

When heterochromatin is further tightly packaged, its name changes to ?

Answer 17

Chromosome

Question 18

1. DNA -> ___ -> mRNA

2. How does RNA splicing form mRNA?

Answer 18

1. Heteronuclear RNA (hnRNA)

2. RNA splicing removes introns and splices together exons to form mRNA

Question 19

1. After mRNA is translated to protein at rough ER they enter ___ and then ___ for further processing
2. The processing at the latter location is referred to as ____

Answer 19

1. RER and golgi (via vesicles that bud off from rER)

2. Post translational modification

Question 20

Constitutive secretory pathway vs. regulated secretory pathway

Answer 20

Both have to do with secretion at the golgi, but constitutive occurs constantly while regulated must be activated

Question 21

Mitochondria

1. Outer membrane allows for what kind of diffusion?
2. Inner membrane?

Answer 21

1. Has small pores so ions and small molecules can diffuse between cytoplasm and intermembrane space
2. Lacks pores - contains ion channels and pumps and transporter proteins

Question 22

3 phases of energy production:

1. Glycolysis converts __ to __. Location?
2. CAC: Product of glycolysis is transported to?
3. ETC and ATP synthase: location?

Answer 22

1. Glucose to pyruvate
2. Mitochondrial matrix
3. Inner membrane of the mitochondria

Question 23

It is important for actin to be located in parts of cells that are?

Answer 23

Growing or changing in shape

Question 24

Main function of intermediate filaments?

Structure?

Answer 24

Used as part structures that attach neighboring cells

Two monomer strands coiled together to for a dimer; dimer then linked into sheet like structure which could to form final rope like structure

Question 25

Basic unit of microtubules is a dimer of 2 proteins: __ and __ which binds to form cylindrical structure Function of microtubules?

Answer 25

Alpha and beta tubulin Long extension of cells that form mitotic spindles and cilia and work with motor proteins to transport items

Question 26

Out of the three components of the cytoskeleton, which have polarity?

Answer 26

Actin and microtubules (not intermediate filaments)

Question 27

Name two motor proteins and which direction do they move?

Answer 27

Kinesin: moves towards plus end Dynein: move towards minus end

Question 28

Two main types of receptors and brief function of each

Answer 28

1. Ionotropic: ligand binds to receptor, opens channel so ions can move through 2. Metabotropic: ligand binds to receptor to cause conformation change which activates an enzyme that is attached to the receptor

Question 29

Very broad pathway of G-protein coupled receptors

Answer 29

Hormone binds to a receptor which activates protein attached to the receptor which then works on the enzyme (to either stimulate or inhibit it)

Question 30

3 mechanisms of internalizing substances? They do this by forming ___

Answer 30

1. Pinocytosis, receptor mediated endocytosis (receptor becomes internalized as well), and phagocytosis 2. Through formation of membrane vesicles

Question 31

The 3 mechanisms for internalizing substances all involve formation of a vesicle. What is the fate of the vesicle after mechanism is complete?

Answer 31

Sometimes vesicle is recycled to the cell membrane Sometimes they can fuse with endosomes which mature into lysosomes

Question 32

Main function of peroxisomes and its enzymes

Answer 32

Peroxisome contain degradative enzymes (similar to lysosomes) Peroxidases (specifically catalase) metabolize hydrogen peroxide (H2O2); beta-oxidase degrades lipids

Question 33

What is an abnormal inclusion? When the abnormal accumulation is in the lysosomes, what is this called? Give an example of a specific disease

Answer 33

Something that should have been broken down (degraded) from pathway that was not Lysosomal storage disease (ex: Tay-Sachs); this happens when things aren’t being broken down in the pathway because of lysosome dysfunction (inherited usually)

Question 34

1. Autophagy would be used to degrade? 2. For this to happen, materials are transported to where in the cell? 3. What are the 3 modes

Answer 34

1. Things inside of the cell (self eating) 2. Lysosome 3. Macroautophagy, microautophagy, and chaperone mediated autophagy

Question 35

Proteosomal pathway is similar to autophagy except? Broad pathway steps?

Answer 35

It is specifically for protein degradation Proteins bind to ubiquitin (chaperone protein), which mediates translocation and entry into proteosomal vesicles which contain proteases.

Question 36

What is the meaning of “fluid mosaic”?

Answer 36

Proteins and lipid rafts have horizontal mobility within the cell membrane (phospholipid bilayer doesn’t limit the movement)

Question 37

Function of rRNA

Answer 37

Helps translate the information in mRNA to protein

Question 38

Give brief overview of the Gs pathway

Answer 38

Hormone is stimulatory by binding to the Rs receptor which has a Gs protein attached. This protein will bind to the enzyme Adenylate Cyclase to convert ATP to cAMP which activates protein kinase A to phosphorylate other intracellular proteins that stimulate certain cell functions

Question 39

Give brief overview of the Gi pathway

Answer 39

Hormone is inhibitory by binding to the Ri receptor which has a Gi protein attached. This protein binds to enzyme Adenylate Cyclase which blocks the conversion of ATP to cAMP, thus reducing protein kinase A activity and reducing its phosphorylation, thus inhibiting certain cell functions

Question 40

Give brief overview of the Gp pathway

Answer 40

~more similar to Gs~ Hormone is stimulatory by activating R receptor that has a Gp protein attached. This protein binds to Phospholipase C and activates it, which cleaves a membrane phospholipid PIP2 into 2 products: DAG and IP3 DAG binds and activates protein kinase A which phosphorylates various proteins IP3 levels are regulated through degradation by phosphatase enzymes; IP3 binds and opens calcium channels (that are embedded in ER); calcium flows from inside ER to cytoplasm where calcium can regulate protein and cell functions

Question 41

Overview of lysosomal degradation pathway

Answer 41

Extra cellular substance binds transmembrane receptor Clathrin proteins form coated pits and vesicles pinch off from membrane Vesicle fuses with Endosome Multivesicular bodies (MVB)(small vesicles) bud off the endosome Endosomes become lysosomes (endosomes are more acidic than cytoplasm, lysosomes are even more acidic than endosomes)