Lectures 13-15 (Exam 4)

Question 1

DNA

Answer 1

Two strands (double helix) held together by nitrogenous bases (A, T, G, C), backbone made of sugar and phosphate

Question 2

Amino acids basic chemistry

Answer 2

R <– sulfur atom
|
Na - C - COOH
|
H

Question 3

Griffith experiment

Answer 3

In 1928, Fredrick Griffith worked with two strands of a bacterium, one pathogenic (harmful) and one harmless. Mixed heat-killed remains of the pathogenic strain with living cells of the harmless strain, some living cells became pathogenic - “transformation”

Question 4

Griffith experiment results

Answer 4

Living S cells - mouse died
Living R cells - mouse healthy
Heat-killed S cells - mouse healthy
Mixture of heat-killed S cells and living R cells - mouse died

Question 5

Avery, McCarthy, and MacLeod

Answer 5

1944 - announced that the transforming substance (from Griffith experiment) was DNA

Experiment: DNA worked in transforming harmless bacteria into pathogenic bacteria

Question 6

Phage

Answer 6

Protein device (outer shell of the phage) that carries DNA (inside the phage) - perfect for determining if genetic material was DNA or protein

Question 7

Hershey-Chase experiment

Answer 7

1952 - performed experiments showing that DNA is the genetic material of a phage known as T2

Designed an experiment showing that only one of the two components of T2 (DNA or protein) enters an E. coli cell during infection - concluded that the injected DNA of the phage provides the genetic information

Question 8

Rosalind Franklin

Answer 8

The woman to actually discover the structure of DNA

Question 9

DNA strands are ____

Answer 9

Antiparallel

Ex.
strand one: phosphate-sugar-G-C-sugar-phosphate
strand two: phosphate-sugar-C-G-sugar-phosphate

Question 10

Transformation

Answer 10

Moving DNA into an organism

Question 11

E. coli cell division

Answer 11

Binary fission

Question 12

E. coli is sensitive to ____

Answer 12

Ampicillin

Question 13

P.C.R. steps

Answer 13

Step 1: Denaturation - heat is applied to the template to separate double-stranded DNA into two single strands - 94 degrees C
Step 2: Annealing - the temperature decreases to that primers can anneal to complementary sequences on the DNA strands - 52 degrees C
Step 3: Extension - taq polymerase binds to each PCR primers and begins adding nucleotides; two copies of original strand is produced - 72 degrees C

Question 14

STRs

Answer 14

Short Tandem Repeats - same region repeated # of times (differs between people)

Question 15

DNA synthesis

Answer 15

Goes from 5 prime to 3 prime always

Question 16

Origin of replication

Answer 16

Place where DNA synthesis begins

Question 17

Helicase

Answer 17

Untwists DNA; creates single stranded DNA

Question 18

Topoisomerase

Answer 18

Cuts knot, releases tension in DNA - corrects DNA ‘overwinding’ cause by helise

Question 19

Primase

Answer 19

Lays down short RNA primers

Question 20

DNA polymerase

Answer 20

Synthesizes the new DNA; uses template strand

Question 21

DNA ligase

Answer 21

Joins DNA fragments; DNA glue

Question 22

Things needed for PCR

Answer 22

Template DNA
Nucleotides
DNA polymerase - Taq pol
Primers
Buffer

Question 23

How DNA is turned into protein - central dogma of biology

Answer 23

DNA
v
mRNA
v
Protein

Question 24

How DNA is turned into mRNA

Answer 24

Transcription

Question 25

How mRNA is turned into protein

Answer 25

Translation

Question 26

Where transcription and translation occurs in prokaryotic cells

Answer 26

Cytoplasm

Question 27

Where transcription occurs in eukaryotic cells

Answer 27

Nucleus - nucleolus

Question 28

Where translation occurs in eukaryotic cells

Answer 28

Cytoplasm or rough ER

Question 29

Transcription takes DNA and creates ____

Answer 29

mRNA

Question 30

Translation takes up mRNA and creates ____

Answer 30

Protein

Question 31

DNA

Answer 31

Double stranded, deoxyribose, A, T, G, C

Question 32

RNA

Answer 32

Single stranded, ribose, A, U, G, C

Question 33

All of life uses the same ____

Answer 33

Genetic code

Question 34

Stages of transcription

Answer 34

1. Initiation 2. Elongation 3. Termination

Question 35

Introns

Answer 35

Noncoding regions - removed during RNA splicing

Question 36

Exons

Answer 36

Eventually expressed, usually translated into amino acid sequences - joined together during RNA splicing

Question 37

Alternative RNA splicing

Answer 37

One gene can join exons in different ways Ex. 1,2,3 , 1,2 , 1,3 , 2,3

Question 38

tRNA

Answer 38

Transfer amino acids to the growing polypeptide in a ribosome

Question 39

Accurate translation steps

Answer 39

1. A correct match between a tRNA and an amino acid (aminoacyl-tRNA synthetase) 2. A correct match between the tRNA anticodon and an mRNA codon

Question 40

Wobble

Answer 40

Flexible pairing at the third base of a codon - second step of translation - allows some tRNAs to bind to more than one codon

Question 41

rRNA

Answer 41

Ribosomal RNA, the two ribosomal subunits of a ribosome (small and large)

Question 42

rRNA binding sites for tRNA

Answer 42

P site - holds the tRNA that carries the growing polypeptide chain A site - holds the tRNA that carries the next amino acid to be added to the chain E site - the exit site, where discharged tRNAs leave the ribosome

Question 43

Okazaki fragments

Answer 43

Fragments from the lagging strand of DNA synthesis - eventually linked together by ligase

Question 44

What is the first amino acid laid down in every protein made?

Answer 44

Methyanine

Question 45

How does a ribosome know when to stop translation?

Answer 45

When there is a stop codon

Question 46

How does transcription start/stop?

Answer 46

Starts: RNA pol binds to DNA template strand - promoter Stop: RNA pol releases DNA template strand - terminator

Question 47

How does translation start/stop?

Answer 47

Start and stop codons - AUG is start, UAA, UAG, or UGA is stop

Question 48

Operon

Answer 48

Entire stretch of DNA that includes the operator, the promoter, and the genes they control

Question 49

Operator

Answer 49

The regulatory "switch" - is a segment of DNA usually positioned within the promotor

Question 50

Promoter

Answer 50

A nucleotide sequence that enables a gene to be transcribed

Question 51

Operon can be switched off by a ____

Answer 51

Protein repressor

Question 52

Protein repressor

Answer 52

Stops gene transcription by binding to operator - stops RNA polymerase

Question 53

Trp operon

Answer 53

E. coli can synthesis the amino acid tryptophan - expressed when tryptophan levels are low, turned off when tryptophan levels are high

Question 54

Repressible operon

Answer 54

Usually on - binding of a repressor to the operator shuts off transcription Trp operon

Question 55

Lac operon

Answer 55

Contains genes that code for enzymes used in the hydrolysis and metabolism of lactose

Question 56

Inducible operon

Answer 56

Usually off - molecule called inducer inactivates the repressor and turns on transcription Lac operon

Question 57

Micro RNAs

Answer 57

Controls gene expression by binding with mRNA

Question 58

RNA interference

Answer 58

Stop protein translation by binding to mRNAs