CHAP 9

Question 1

Describe mRNA

Answer 1

Reads 5’–>3’

Triplet code

continuous and non-overlapping

Question 2

Describe rRNA

Answer 2

The most abundant in cells (80%)

Some have structural roles

Others have enzymatic roles (ribozyme)

Make up over 50% of ribosome

Question 3

Where are rRNAs transcribed and assembled?

Answer 3

Into the ribosome in the nucleolus

Question 4

Larger precursor rRNA is transcribed and processed into where?

Answer 4

the smaller RNAs

Question 5

Describe tRNA

Answer 5

ALL have a 5’-CCA-3’ at their 3’ end which is the amino acid binding site

each tRNA carries an amino acid that corresponds to its anti-codon

Genetic code

Question 6

How do tRNAs translate the language?

Answer 6

By codon-anti-codon binding

Question 7

What is the structure of codon-ani-codon binding?

Answer 7

Anti-parallel binding

Ati-codons writen 3’–>5’

Question 8

How are tRNAs charged?

Answer 8

By aminoacyl-tRNA synthetases

Question 9

What does aminoacyl-tRNA synthetases have?

Answer 9

Two proofreading steps to minimize error rate (PP and AMP)

Question 10

True or false: tRNAs bind to more than one codon

Answer 10

True

Question 11

Code degeneracy is due to what?

Answer 11

tRNA wobble

Question 12

What are the factors of translation?

Answer 12

Ribosome needs to locate translation start

First tRNA needs to be brought to the start site

Ribosome needs to assemble

Aided by initiation factors

Question 13

Describe initiation in bacteria

Answer 13

Translation occurs at the same time as transcription

There are three initiation factors

Shine-Dalgarno sequence

First amino acid is N-formyl-methionine

Question 14

Describe the three initiation factors in bacterial initiation

Answer 14

IF-1: blocks tRNA from A site

IF-2 brings in amino acid

IF-3: prevents binding

Question 15

Describe the Shine-Dalgarno sequence

Answer 15

Is the ribosome binding site in the 5’-URT of mRNA

16s rRNA is bound to it

Question 16

Describe initiation in eukaryotes

Answer 16

Translation only occurs after mRNA processing and transport to the cytoplasm

7 initiation factors

First amino acid is methionine on a specialized initiation tRNA

5’ cap is essential

IF’s at CAP bind to PABPs to circularize the mRNA

Question 17

Describe termination

Answer 17

No tRNAs bind to stop codons

Two release factors (RF) bind to stop codons

Hydrolysis results in removal of peptide chain

Question 18

What are the stop codons?

Answer 18

UAA, UGA, UAG

Question 19

What are mutations that can affect termination?

Answer 19

Nonsense mutaton

Nonsense suppressor mutation in tRNA gene

Question 20

What happens after translation?

Answer 20

Folding

Sorting

Modification

Question 21

What is the larger and smaller portion of the eukaryotic ribosome? What is the total size?

Answer 21

LP: 60S

SP: 40S

Total: 80S

Question 22

How many alpha and beta chains does hemoglobin have?

Answer 22

2 alpha chains

2 beta chains

Question 23

What direction is the primary structure read in?

Answer 23

N-C

Question 24

What is the start codon?

Answer 24

AUG

Question 25

How many codons are there?

Answer 25

64

Question 26

How many amino acids are made from the codons?

Answer 26

20

Question 27

What does APE stand for?

Answer 27

Aminoacyl site Peptidyl site Exit site This is the order the stand goes through as the ribosome travels along its length

Question 28

In wobble pairing, what can G and U bind to?

Answer 28

G: C or U U: A or G

Question 29

What can I (inosine) bind to?

Answer 29

A, C, or U

Question 30

What can be used to detect DNA in vitro?

Answer 30

Southern bolt (probe DNA or RNA frags.) PCR (probe DNA primers)

Question 31

What can be used to detect DNA in vivo?

Answer 31

Fluorescence in situ hybridization (FISH) Probe DNA primers

Question 32

What can detect RNA in vitro?

Answer 32

Northern bolt (Probe DNA/RNA frags.) Reverse transcription-PCR (RT-PCR) (Probe DNA primer)

Question 33

What can be used to detect RNA in vivo?

Answer 33

In situ hybridization (Probe DNA/RNA frags.)

Question 34

What can be used to detect proteins in vitro?

Answer 34

Western bolt (Probe anti-body)

Question 35

What can be used to detect proteins in vivo?

Answer 35

Immunofluorescence (Probe anti-body)

Question 36

What is Northern bolt?

Answer 36

Purified RNA fragments from a biological sample (such as blood or tissue) are separated by using an electric current to move them through a sieve-like gel or matrix, which allows smaller fragments to move faster than larger fragments. The RNA fragments are transferred out of the gel or matrix onto a solid membrane, which is then exposed to a DNA probe labeled with a radioactive, fluorescent or chemical tag. The tag allows any RNA fragments containing complementary sequences with the DNA probe sequence to be visualized within the Northern blot

Question 37

What is Southern bolt?

Answer 37

Purified DNA from a biological sample (such as blood or tissue) is digested with a restriction enzyme(s) The resulting DNA fragments are separated by using an electric current to move them through a sieve-like gel or matrix, which allows smaller fragments move faster than larger fragments. The DNA fragments are transferred out of the gel or matrix onto a solid membrane, which is then exposed to a DNA/RNA probe labeled with a radioactive, fluorescent or chemical tag. The tag allows any DNA fragments containing complementary sequences with the DNA probe sequence to be visualized within the Southern blot.

Question 38

What is Western bolt?

Answer 38

The method involves using gel electrophoresis to separate the sample's proteins. The separated proteins are transferred out of the gel to the surface of a membrane. The membrane is exposed to an antibody specific to the target protein. Binding of the antibody is detected using a radioactive or chemical tag. A western blot is sometimes used to diagnose disease.

Question 39

Describe Elongation

Answer 39

EF-Tu brings in charged amino acids Peptide is added to the aa in the A site EF-G pushes the ribosome along the mRNA one codon (3nts) NRG for both peptide bond formation and ribosome movement comes from GTP hydrolysis

Question 40

Describe proteins that are co-translationally sorted

Answer 40

Destinated for the membrane, secretion of lysosomes signal peptide (or sequence) is short stretch of hydrophobic amino acids very near the N-terminus Signal is removed after translation