Midterm 2

Question 1

How is genetic code translated?

Answer 1

By two adaptors that are one after another

Question 2

Eukaryotic ribosomes are large complexes made of…

Answer 2

4 rRNA’s and more than 40 small proteins

Question 3

Each ribosome has a binding site for…

Answer 3

mRNA and three binding sites for tRNA

Question 4

How many steps does translation have?

Answer 4

4

Question 5

What does initiation of protein synthesis in eukaryotes require?

Answer 5

Translation initiation factors and a special initiator tRNA

Question 6

What stops translation?

Answer 6

A stop codon

Question 7

What marks proteins for degradation in the proteosome?

Answer 7

The ubiquitin protein

Question 8

True or False?

Some proteins require modification after translation to work properly.

Answer 8

True

Question 9

Where do transcriptional regulators bind in DNA

Answer 9

The major groove of the DNA

Question 10

True or False?

Gene activation always occurs at the transcription start site.

Answer 10

False.

It can occur at a distance from the start site.

Question 11

What causes local alterations in chromatin structure to stimulate transcription initiation?

Answer 11

Eukaryotic transcription activators

Question 12

Transcriptional regulators can work in a _____ manner to control gene expression.

A. Cooperative
B. Competitive
C. Non-competitive

Answer 12

A. Cooperative

Question 13

True or false?

A single transcriptional regulator can control the expression of many genes in a coordinated fashion.

Answer 13

True

Question 14

The combination of transcriptional regulators induces…?

Answer 14

A differentiated cell to de-differentiate into a pluripotent stem cell

Question 15

What is the first stage of Cellular Metabolism?

Answer 15

Break down of food into simple subunits

Question 16

What is the second stage of Cellular Metabolism?

Answer 16

Break down of the subunits to Acetyl CoA with some production of ATP and NADH

Question 17

What is the third stage of Cellular Metabolism?

Answer 17

The complete oxidation of the Acetyl CoA to H2O and CO2 into large amounts of ATP in the mitochondria

Question 18

Sugars are oxidized ___ to CO2 and water.

Answer 18

Stepwise

Question 19

What are the products of the breakdown of glucose in glycolysis?

Answer 19

Pyruvate, ATP, and NADH

Question 20

What converts pyruvate into Acetyl CoA and where does it happen?

Answer 20

Pyruvate decarboxylase in the mitochondrial matrix

Question 21

What are the products of one Citric Acid Cycle?

Answer 21

3 NADH, 1 GTP, and 1 FADH2

Question 22

What is the last step of food catabolism?

Answer 22

Oxidative phosphorylation

Question 23

Mitochondria often cluster at or near site of…

Answer 23

High ATP utilization

Question 24

ATP Synthase is a reversible motor meaning that…

Answer 24

It is capable of ATP synthesis and ATP hydrolysis

Question 25

Nuclear membranes and the ER probably evolved from...

Answer 25

Invaginations of the plasma membrane

Question 26

Mitochondria may have originated as...

Answer 26

An engulfed prokaryotic cell

Question 27

What are the 3 mechanisms that membrane enclosed organelles use to import proteins?

Answer 27

1. Transport through nuclear pores 2. Transport across membranes 3. Transport by vesicles

Question 28

What helps direct proteins towards their destinations?

Answer 28

Signal sequences

Question 29

What acts as the "gate" that selects which proteins can enter and exit the nucleus?

Answer 29

The nuclear pore complex

Question 30

Where does the energy that drives nuclear transport come from?

Answer 30

GTP hydrolysis

Question 31

What happens to mitochondrial precursor proteins during import?

Answer 31

They get unfolded

Question 32

What is the function of chaperone proteins?

Answer 32

They prevent misfolded or damaged proteins from leaving the ER

Question 33

Extracellular signal molecules can bind to either ____ receptors or _____ receptors.

Answer 33

Cell-surface, intracellular

Question 34

What are the 4 forms of intercellular signaling?

Answer 34

Endocrine, paracrine, synaptic, and contact-depenedent

Question 35

True or False? Extracellular signals can only act very fast.

Answer 35

False, extracellular signals can act fast or slow

Question 36

Animal cells depend on (multiple) or (single) extracellular signals to tell them what to do.

Answer 36

Multiple

Question 37

The neurotransmitter acetylcholine induces which of the following responses? A. Decreased heart rate B. Saliva secretion C. Skeletal muscle contraction D. All of the above

Answer 37

D. All of the above

Question 38

What is the role of nitric oxide in smooth muscle cells?

Answer 38

It causes relaxation of the smooth muscle cells

Question 39

Signal molecules that bind to nuclear receptors are usually ____ and ___.

Answer 39

Small and hydrophobic

Question 40

What are the three class of cell-surface receptors?

Answer 40

1. Ion-channel-coupled receptors 2. G-protein-coupled receptors 3. Enzyme-coupled receptors

Question 41

G protein linked receptors can cause release of ...

Answer 41

Second messenger signaling molecules

Question 42

What increases rapidly in response to an extracellular signal in nerve cells?

Answer 42

Cyclic AMP

Question 43

What does Adrenaline stimulate in skeletal muscle cells?

Answer 43

Glycogen breakdown

Question 44

What is the increase of cytosolic Ca++ triggered by?

Answer 44

The fertilization of an egg by a sperm

Question 45

What is the Notch receptor?

Answer 45

A transcription regulator

Question 46

True or False? Intracellular signaling proteins can only respond to one signal at a time.

Answer 46

False, the signaling proteins can integrate multiple signals at once

Question 47

What is cytoskeleton made up of and what does it do?

Answer 47

A dense network of protein polymers and it controls the shape of and biochemical activity of the cell

Question 48

What shape do Intermediate Filaments look like?

Answer 48

String and ropes

Question 49

What do Intermediate filaments do for the nuclear envelope?

Answer 49

Supports and strengthens

Question 50

What do microtubules grow out of?

Answer 50

An organizing center

Question 51

What shape do microtubules take?

Answer 51

Hollow tubes

Question 52

What are microtubules made of?

Answer 52

Tubulin subunits

Question 53

What do microtubules do in nerve axons?

Answer 53

They guide the transport of molecules and molecular complexes

Question 54

What are the two molecular motors that move along microtubules?

Answer 54

Kinesins and dyneins

Question 55

What do actin filaments allow animal cells to do?

Answer 55

Take on many shapes and have many functions

Question 56

What are actin filaments?

Answer 56

Thin, flexible protein threads

Question 57

What decreases the stability of the actin polymer?

Answer 57

ATP hydrolysis

Question 58

What are two ways polymer length is regulated?

Answer 58

Treadmilling (actin filaments) and dynamic instability (microtubules)

Question 59

What do actin-binding proteins control?

Answer 59

The action of actin filaments in vertebrate cells

Question 60

How do actin filaments drive cells to move forward?

Answer 60

By generating forces in the cortex of the cell

Question 61

Which motor protein functions with actin filaments?

Answer 61

Myosin-I