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BIO 107 > EXAM 4 > Flashcards

EXAM 4 Flashcards

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Biology 101 flashcards
1
Q

The composition of DNA was well established by the 1950s. Models showed different arrangements of the components and sometimes introduced additional ones (such as magnesium), but all contained ______, ______, and ______.

A

sugars, phosphates, & bases

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2
Q

Chargaff’s observation suggested that _ would always pair with _ and _ would always pair with _ in a DNA molecule.

A

A-T and G-C

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3
Q

Adjacent nucleotides in the sugar-phosphate backbone are held together by the strongest type of chemical bond, __(2)__.

A

covalent bonds

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4
Q

The bonds or interactions that hold together complementary bases from opposite strands of DNA are __(2)__. These allow complementary DNA strands to _____ during S phase replication.

A

H-bonds - “unzip”

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5
Q

The bonds or interactions between stacked nucleotide units that help hold the DNA molecule together are ________.

A

van der Waals

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6
Q

The ___ end of a DNA strand has an exposed -OH group, and the ___ end has a phosphate group.

A

3’ - 5’

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7
Q

The T2 phage consists of a protein coat and DNA. It is the ____ that contains P.

A

DNA

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8
Q

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage’s genetic material.

A

labeled DNA - DNA

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9
Q

To elongate the lagging strand in the mandatory direction, DNA pol III must work along the other template strand in the direction __(2)__ the replication fork.

A

away from

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10
Q

The enzyme that can replicate DNA is called __(2)__.

A

DNA polymerase

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11
Q

_______ are enzymes that untwist the double helix at the replication forks, separating the 2 parental strands and making them available as template strands.

A

Helicases

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12
Q

The leading strand is built ______, but the lagging strand is built in _______.

A

continuously - pieces

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13
Q

The untwisting of the double helix causes tighter twisting and strain ahead of the replication fork, but _______ helps relieve this by breaking and rejoining DNA strands.

A

topoisomerase

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14
Q

The initial nucleotide chain that is produced during DNA synthesis is actually a short stretch of ____, not DNA. This ____ chain is called a primer and is synthesized by the enzyme _____.

A

RNA x 2 - primase

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15
Q

DNA polymerase can only add nucleotides to the ____ end of a new DNA strand.

A new DNA strand can only ELONGATE in the ____ to ____ direction.

A

3’ / (5’ to 3’)

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16
Q

Multiple primers are needed for the _____ strand, but only 1 (polymerase III) is needed for the _____ strand.

A

lagging - leading

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17
Q

______ lays down RNA primer. ______ starts at end of RNA primer and adds DNA nucleotides.

A

Primase - DNA Polymerase III

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18
Q

DNA polymerase 1 is involved in the _____ of _____ from the fragments and replacing the gap by relevant nucleotides, whereas DNA polymerase 3 is mainly involved in the ______ of the leading and lagging strands.

A

removal of primers

synthesis

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19
Q

DNA _____ closes the gap between fragments A & B on the _____ strand.

A

ligase - lagging

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20
Q

The correct DNA replication model is _____ and produces 2 double helices: ____ dark blue and ____ light blue strand per double helix in the 1st replication.

The 2nd replication produces 4 double helices: 2 of them each have 1 dark & 1 light blue strand, while the other 2 both have ____ blue strands.

A

semiconservative - 1 & 1 - light blue (or daughter DNA)

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21
Q

The evolutionary significance of altered DNA nucleotides is that _____ are the source of genetic _____ upon which natural selection operates. Sequence changes may become ____ and be _____ down to next generation.

A

mutations - variation

permanent - passed

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22
Q

If chromosomes of germ cells became shorter each round of cell division, this could cause essential genes to be _____ from the ____ they produce. The enzyme _____ catalyzes the lengthening of telomeres in germ cells.

A

missing - gametes - telomerase

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23
Q

Not all cells have active telomerase (catalyze lengthening of telomeres in germ cells), but high ____ cells do.

In cancer cells, telomerase can be turned __(2)__ and allow division when they shouldn’t!

A

turnover

back on

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24
Q

Proteins called ____ are responsible for the first level of DNA packing in chromatin and there are ____ types.

A

histones - 4

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25
Q

_____ are like beads on a string and consists of DNA wound 2x around a protein core of 8 _____.

A

Nucleosomes - histones

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26
Q

Because of its compaction, ______ DNA is largely ______ to the machinery in the cell responsible for transcribing the genetic information coded in the DNA.

A

heterochromatic - inaccessible

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27
Q

Understanding DNA structure and replication makes genetic _____ possible. The 2 strands of DNA are _____ to each other, which is the basis for nucleic acid ______.

A

engineering - complementary - hybridization

28
Q

Common tools for genetic engineering include recombinant ____, DNA c____, r_____ enzymes, gel e____, and PCR.

A

DNA - cloning - restriction - electrophoresis

29
Q

Gene cloning/engineering rely on use of ______ enzymes that cut DNA molecules at specific locations.

A

restriction

30
Q

DNA is ______ to messenger RNA (mRNA), and the mRNA is _____ to proteins on the ribosomes.

A

transcribed - translated

31
Q

Transcription begins when a molecule of RNA polymerase binds to a _____. Then RNA poly ____ gene. Once it reaches the ______, it exits the gene and releases RNA.

A

promoter - transcribes - terminator

32
Q

RNA molecules do not have () or ____ like DNA does. Instead it has () or ____. Base pairing between DNA & DNA is always A-_ and G-_, but when DNA pairs w/ RNA it is A-_ and G-_.

A

T or thymine - U or uracil

A-T and G-C / A-U and G-C

33
Q

Synthesis of _____ is not directly coded in DNA, but it is for mRNA, p_____, & DNA.

A

organelles - proteins

34
Q

A gene has 2 main parts, a regulatory region containing a _____ and a transcription region which contains the _____ information for a protein product.

A

promoter - coding

35
Q

A sequence of 3 nucleotides on an mRNA molecule is called a ______. What codon codes for _____ and functions as a start signal?

A

codon - Methionine (met) - AUG

36
Q

When RNA is modified before translation, it is called RNA ______. During this time, a __(2)__ nucleotide is added to the ____ end as a “cap”.

A

processing - modified guanine - 5’

37
Q

During RNA processing, a _____ tail is added to the ____ end of the RNA.

A

poly-A - 3’

38
Q

______ delete portions of the RNA called _____ and connect remaining segments called ______ or expressed regions.

A

Spliceosomes - introns

exons

39
Q

Translation or protein _______ takes place in the ______ at the _____.

A

synthesis - cytosol - ribosome

40
Q

________ is the process by which the ribosome slides down the mRNA so a new cycle of elongation can begin.

A

Translocation

41
Q

Triplets of RNA bases are called _____. A ribosome facilitates the pairing of each mRNA ______ w/ a particular tRNA a_______.

A

codons - codon - anticodon

42
Q

What can RNA polymerases (i.e., primase) do that DNA polymerases cannot?

A

RNA polymerases (primase) can add new nucleotides w/o the 3’ -OH group, but DNA polymerases cannot.

43
Q

Gene cloning is useful for two basic purposes: to make many ______ of (or amplify) a particular gene and to produce a _____ product from it.

A

copies - protein

44
Q

Gene Cloning using copies of GENE:
1. Gene for _____ resistance is inserted into plant.
2. Gene is used to alter ______ for cleaning up _____ waste.

A

pest

bacteria - toxic

45
Q

Gene Cloning using harvested PROTEIN product:
1. HGH used to treat ______ growth.
2. Protein dissolves blood _____ in heart attack therapy.

A

stunted

clots

46
Q

Gene cloning and genetic engineering generally rely on the use of enzymes that cut DNA molecules at a _______ number of specific locations. These enzymes are called __(2)__.

A

limited - restriction enzymes

47
Q

Proteins are the link between genotype and phenotype.

Gene expression is the process by which DNA directs the synthesis of _______ (or, in some cases, just _____).

The ______ of genes that code for proteins includes two stages: transcription and translation.

A

proteins - RNAs

expression

48
Q

Proofreading corrects many errors, but sometimes a few get through. Mismatch ______ helps catch and remove these errors right after DNA synthesis. __(2)__ then replaces the missing errors.

A

repair - DNA polymerase

49
Q

Some genes don’t encode ______. Some genes actually encode functional ______ molecules instead.

A

polypeptides - RNA

50
Q

The genetic code is r______, not _______, and nearly ______.

A

redundant - ambiguous - universal

51
Q

The start codon for RNA is always __ U __ that codes for the AA ______.

A

AUG - Met

52
Q

The 3 stop codons are UAA, UAG, and _____.

A

UGA

53
Q

The codons are read by the translation machinery in the ___ to ___ direction along the mRNA.

A

5’ –> 3’

54
Q

The 3 stages of transcription include: initiation, ______, and t______.

A

elongation - termination

55
Q

Several transcription _____ bind to the DNA.
RNA poly II attaches to and initiates transcription at the ______.
Transcription initiation _____ forms.
The stretch of DNA downstream from the promoter that is transcribed into an RNA molecule is called a __(2)__.

A

factors - promoter - complex - transcription unit

56
Q

There are 3 RNA polymerases:

RNA poly I makes _____ transcripts.

RNA poly II makes _____ which code for proteins.

RNA poly III makes _____ and plays a role the translation process.

A

rRNA

mRNA

tRNA

57
Q

During termination of transcription:

Bacteria trxn proceeds through a ______ sequence in the DNA and the transcript goes straight to translation.

In eukaryotes, RNA polymerase II transcribes a sequence on the DNA called the _______ signal sequence, which specifies a “signal” (AAUAAA) in the pre-mRNA. The pre-mRNA requires further _____ before translation.

A

terminator

polyadenylation - processing

58
Q

The modified ends may promote the export of _____ from the nucleus, and they help protect it from ______.

A

mRNA - degradation

59
Q

A modified __(2)__ is added to the ___ end of the pre-mRNA, which is synthesized first, after the first 20–40 nucleotides have been transcribed.

A

guanine nucleotide - 5’

60
Q

At the ___ end, an enzyme then adds 50–250 more adenine (A) nucleotides, forming a __(2)__.

A

3’ - poly-A tail

61
Q

The stretch of DNA downstream from the promoter that is transcribed into an RNA molecule is called a __(2)__.

A

transcription unit

62
Q

What mediates the binding of RNA polymerase and the initiation of transcription? (a collection of proteins)

A

transcription factors

63
Q

The 5′ UTR and 3′ UTR do not code for _______, but they are parts of ________ because they remain in the mRNA.

A

protein - exons

64
Q

_______ RNA ______ is a type of eukaryotic gene______ at the RNA-processing level in which different mRNA molecules are produced from the same primary ______, depending on which RNA segments are treated as exons and which as introns.

A

alternative RNA splicing - regulation - transcript

65
Q

BC of alternative RNA splicing, the number of different protein products an organism produces can be much greater than its number of _______.

A

genes

66
Q

_____ translates the “message” from mRNA and transfers __(2)__ from the cytoplasm to the growing polypeptide in a _____ via ___ bonds.

A

tRNA - amino acids - ribosome - H-bonds

BIO 107 (4 decks)

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