Class lectures mod 5 (exam 3)

Question 1

amino acids

Answer 1

monomer building blocks for polypeptides

Question 2

polypeptides

Answer 2

polymers of amino acids

Question 3

mRNA

Answer 3

specifies the order in which amino acids are added to the polypeptide chain

Question 4

tRNA

Answer 4

the “translator” that decodes the information in the mRNA nucleotides to the polypeptide (amino acdis)

Question 5

ribosome

Answer 5

the structure in the cytoplasm where translation takes place

Question 6

Codons in translation with mRNA and tRNA

Answer 6

mRNA: has a codon of which amino acids goes where
tRNA: has an anticodon on one end and the amino acid on another end

Question 7

aa-tRNA

Answer 7

a tRNA molecule bound to an amino acid called an amino-acyl TRNA

Question 8

some special codons: AUG

Answer 8

-specifies met (methionine) and starts translation, so every protein that has a Met as the first amino acid

Question 9

special codons: UAA, UAG, UGA

Answer 9

-they are stop codons and they specify where translation should end
-there is no tRNA with the corresponding anti-codons

Question 10

what are the stages of translation

Answer 10

-initiation
-elongation
-termination

Question 11

internal membrane system

Answer 11

separates the cell into compartments

Question 12

address labels for the proteins reside in the

Answer 12

amino acid sequence

Question 13

while in the process of translation, proteins targeted to the endomembrane system

Answer 13

have a “tag” that tells the ribosome where this mRNA should be translated while sitting on the ER

Question 14

signal sequence

Answer 14

-“tag”
-stretch of amino acids that is recognized by receptors on the cytosolic surface of the ER

Question 15

secretory proteins initate

Answer 15

translation on ribosomes in the cytosol

Question 16

sequence for address labels for proteins

Answer 16

1) signal recognition particles (SRP) binds to the signal peptide
2) the SRP brings the ribosome to the ER by binding to the receptor on the ER and the receptor and other proteins form a pore through ER
3) ribosome translates the polypeptide as it moves through the ER pore
4) signal peptidase snips off signal peptide and translation goes until it is done
5) polypeptide released and may have further processing

Question 17

subcellular fractionation

Answer 17

-how we know protein goes into cell
-cell compartments are separated from one another by density and he speed that is needed to force them to the bottom of the centrifuge tube

Question 18

larger, dense compartments, will pellet

Answer 18

LOWER speeds than less dense compartments

Question 19

soluble proteins in the cytosol don’t form a pellet at

Answer 19

high speeds so we can separate the different compartments in the cell

Question 20

western blotting

Answer 20

-proteins w/in a compartment are separated from one another by gel electrophoresis that separates proteins based on size and charge

Question 21

once we have different compartments, we can transfer proteins onto

Answer 21

a membrane and then stain with an antibody that recognizes the protein of interest
-we will only see staining in the lane containing proteins from the compartment in which the protein is located

Question 22

some proteins are targeted to organelles

Answer 22

AFTER they have been translated

Question 23

proteins bound for secretion are targeted to the secretory pathway

Answer 23

WHILE in translation

Question 24

every time a cell divides it must

Answer 24

accurately replicate the genetic information in the DNA so it can be passed onto the 2 daughter cells

Question 25

DNA must be

Answer 25

consistently replicated and the genetic information has to be readily transferable for the next generations

Question 26

Matthew Meselson and Franklin Stahl conducted a

Answer 26

pulse-chase experiment to determine the correct model of the DNA

Question 27

what are the steps from Meselson and Stahl's experiment

Answer 27

-extract DNA to form heave and light cultures - mix DNA together and spin it (centrifuge)

Question 28

if DNA replication is semiconservative

Answer 28

it makes 2 new DNA double helices containing one old strand and one new strand

Question 29

if DNA replication is conservative

Answer 29

-theoretical model -the original parental DNA strands remains completely intact -result is one completely new strand and one old strand

Question 30

if DNA replication is dispersive

Answer 30

-hypothetical model -parental DNA breaks into fragments and serves as a template for new DNA segments -both daughter DNA molecules containing mixture of old and new strands, making a "hybrid"

Question 31

mitosis

Answer 31

nuclear division associated with somatic cells, producing 2 genetically identical daughter cells

Question 32

meiosis

Answer 32

nuclear division that produces cells that develop into gametes

Question 33

daughter cells have two times more DNA than mother, so

Answer 33

therefore cells need to replicate DNA before division

Question 34

spindle checkpoint

Answer 34

mechanism that ensures chromosome is equally separated during cell division

Question 35

how do we know what stage of the cell cycle the cell is?

Answer 35

calculate the mitotic index: the proportion of cells undergoing mitosis in a population of cells

Question 36

DNA = 2N (2C)

Answer 36

the DNA content of cell prior to replication

Question 37

DNA = 2N (4C)

Answer 37

has twice the DNA content of the cells prior to replication

Question 38

mitosis 6 stages

Answer 38

1) interphase 2) prophase 3) prometaphase 4) metaphase 5) anaphase 6) telophase and cytokinesis