Cell And Molecular Bio Midterm

Front 1

DNA and RNA are polymers of what type of nucleotides?

Back 1

monomeric unit

Front 2

Each nucleotide is made up of what three components?

Back 2

1. a sugar
2. a phosphate
3. a base

Front 3

What are the 4 bases found in DNA?

Back 3

A G C T

Front 4

What are the 4 bases found in RNA?

Back 4

A G C U

Front 5

How do DNA and RNA differ?

Back 5

at the 2' carbon
RNA has a hydroxyl group (ribose)
DNA does not (deoxyribose)

Front 6

Can RNA form double strands?

Back 6

yes, but it is generally found as a single stranded molecule in cells

Front 7

How are the two strands of a double helix DNA molecule oriented?

Back 7

wrapped around each other in an antiparellel orientation (one strand going 5' to 3' and the other going from 3' to 5')

Front 8

What are the two purines?

Back 8

A and G

Front 9

What are the three pyrimidines?

Back 9

T, U, and C

Front 10

What is base pairing in DNA?

In RNA?

Back 10

A-T C-G

A-U C-G

Front 11

What can homologous regions of DNA be used for?

Back 11

they can be compaired among different species to determine phylogenetic relationships

Front 12

Closely related organisms contain similar DNA compliments, however.....

Back 12

they are often arranged differently on the chromosomes of each species

Front 13

What functions can RNA carry out?

Back 13

gene expression, catalytic activity, or signaling

Front 14

What are the 3 divisions, or domains the living world is made up of?

Back 14

bacteria, archea, and eukaryotes

Front 15

What are the 4 main processes for generating change in a genome?

Back 15

1. Intragenic mutation (single base change)
2. Gene duplication
3. DNA segment shuffling
4. Horizontal transfer (from one cell to another)

Front 16

What is the difference between bacteria and eukaryotes with transcription and translation?

Back 16

coupled in bacteria

in eukaryotes: the two processes are separated by a nuclear membrane

Front 17

What usually happens to bacterial genes?

Back 17

they are clustered into groups (operons) that are transcrived as a single unit

Front 18

How are eukaryotic genes often broken up?

Back 18

with regions of noncoding DNA (introns) between regions of coding DNA (exons)

Front 19

When comparing the same gene in several closely related species, what will you notice about the exons and introns?

Back 19

exons will generally be very similar (conserved)
introns will vary in size and content

Front 20

How are bacterial chromosomes organized?

Back 20

densely packed with genes leaving very little DNA that is non-coding

Front 21

T/F Most of the DNA in higher eukaryotes including humans codes for proteins

Back 21

False, most does not code for proteins

Front 22

Most of the human genome is made up of what?

Back 22

repeated sequences

many are mobile and can move around in the genome

Front 23

Bacterial chromosomes are _____ and eukaryotic chromosomes are ______

Back 23

circular
linear

Front 24

Has the human genome been completed?

Back 24

Yes, along with a large number of other organisms

Front 25

Is it possible to construct a metabolic pathway?

Back 25

Yes, and you can compare them with other organisms by examining their entire genome content

Front 26

How can genes be grouped into families?

Back 26

based on similar (homologous) sequences found in different organisms

Front 27

Where can homologous sequences be found?

Back 27

in genes of the same organism that carry out different bu similar functions

Front 28

T/F Genes that have similar functions in very distantly related organisms can have similar sequences (homology).

Back 28

True

Front 29

What is used as a template to synthesize RNA during transcription?

Back 29

DNA

Front 30

What is RNA used for during translation?

Back 30

to code for protein molecules

Front 31

What is reverse transcription?

Back 31

when RNA is used as a template for DNA synthesis

Front 32

T/F Protein is used as a template to synthesize RNA or DNA

Back 32

FALSE!! protein is never used, but RNA and DNA can be used

Front 33

Each 3 nucleotides in an mRNA (codon) codes for what?

Back 33

one amino acid

Front 34

How many potential reding frames are there in each RNA molecule?

in double stranded DNA?

Back 34

3

6

Front 35

What are the 3 major types of RNA (based on their function)

Back 35

r RNA- structural component of the ribosome

mRNA- a copy of genetic information from a gene that is used during translation to specify (code for) a specific protein

tRNA- transfer the 3 base coden on an mRNA into an amino acid on a ner polypeptide

Front 36

When is tRNA used?

Back 36

during translation as a bridge between the mRNA and the synthesized protein

Front 37

How can phylogentic relationships of different organisms be compared?

Back 37

by comparing the DNA sequence of similar genes in the two organisms

Front 38

What is DNA polymerase?

Back 38

it's a DNA dependent (uses DNA as a template) DNA synthesizing enzyme

Front 39

What is RNA polymerase?

Back 39

it's a DNA dependent RNA synthesizing enzyme

Front 40

What is reverse transcriptase?

Back 40

an RNA dependent DNA synthesizing enzyme

Front 41

What is primase?

Back 41

a DNA dependent RNA polymerase

Front 42

What does primase do?

Back 42

synthesizes a small RNA "primer" that can be used by the DNA polymerase to elongate the chain

Front 43

What does DNA polymerase do?

Back 43

minimizes the number of mistakes by using a 3' to 5' exonuclease (or proofreading) activity that is part of the same protein

Front 44

Which direction will DNA polymerase synthesize?

Back 44

5' to 3' along with all other nucleic acid polymerases

Front 45

What happens during replication?

Back 45

each new nucleotide is added to the 3' carbon on the last nucleotide of the new DNA chain

Front 46

During what phase is DNA synthesized in eukaryotes?

Back 46

S phase

Front 47

The base component of each nucleotide is connected to the sugar at which carbon?

Back 47

the 1'

Front 48

The adjacent nucleotides in a DNA chain are attached at which carbons?

Back 48

5' and 3'

Front 49

Which carbon differs between RNA and DNA?

Back 49

2'

Front 50

What is DNA polymerase?

Can it initiate synthesis?

Back 50

it's an elongating enzyme

no

Front 51

What is required for elongation of a new strand when using the DNA polymerase?

Back 51

a primer

Front 52

Bacterial chromosomes contain how many origins of replication?

Back 52

one

Front 53

How does DNA synthesis proceed in bacterial chromosomes?

Back 53

in both directions away from the origin until the two replication forks meet at a specific sequence on the other side of the chromosome

Front 54

Can new rounds of DNA replication begin before the previous round is completed in bacteria?

Back 54

yes

Front 55

How many origins of replication do eukaryotic chromosomes have?

Back 55

many that may change during the development of the organism

Front 56

Can new rounds of replication start before the previous round is completed in eukaryotes?

Back 56

no, new rounds do not start until after the cell divides

Front 57

What are special structures placed on each end of the chromosomes?

Back 57

telomers

Front 58

How are telomers constructed?

Back 58

with the enzyme telomerase that uses an RNA template to synthesize a short repeated DNA sequence at the ends of chromosomes

Front 59

Do the two polymerase molecules on opposite DNA strands move towards each other or away from each other?

Back 59

Opposite because they both go in the 5' to 3' direction

Front 60

What does helicase do?

Back 60

unwinds the 2 DNA strands before polymerization of the new strands

Front 61

What do single-stranded binding proteins do?

Back 61

keep the two complementary strands for reforming a double helix

Front 62

The polymerase on the leading strand moves toward what?

what about the polymerase on the lagging strand?

Back 62

Leading: replication ford

lagging: away from it

Front 63

How is the lagging strand synthesized?

Back 63

in short (okizaki) fragments

Front 64

What does primase do?

Back 64

it initiates synthesis of each Okizaki fragment by making a short RNA primer

Front 65

How is the leading strand synthesized?

Back 65

the continuous movement of the DNA polymerase along the template

Front 66

What does the methylation of DNA signal?

Back 66

that the DNA is unreplicated and is ready to be used as a template for the next round of synthesis

Front 67

What are 4 things a PCR reaction requires?

Back 67

1. a set of primers
2. a target DNA sequence as a template
3. taq DNA polymerase
4. nucleotides

Front 68

What happens for each cycle during a PCR reaction?

Back 68

the product of the previous cycle is used as a template for the next round of synthesis resulting in an exponential increase in the amount of DNA synthesized

Front 69

PCR is carried out in a _____

Back 69

thermocycler
it cycles through a series of temperatures

Front 70

What is the Taq DNA polymerase used for in PCR?

Back 70

it's stable at high temps, allowing the DNA to be heat denatured, to separate the strands without destroying the enzyme

Front 71

How is PCR analyzed? Why?

Back 71

by gel electrophoresis because there is a large amount of the PCR product available after the PCR reaction

Front 72

what are the 4 events that can generate new or modified genes?

Back 72

1. point mutations in the coding region that change the amino acid composition of the protein
2. duplication of the entire gene
3. mixing of segments of one gene with segments of another gene- segment shuffling
4. transfer of genes between two organisms- horizontal gene transfer

Front 73

T/F Many genes belong to gene families that share homologous regions. These regions usually code for proteins that carry out similar functions

Back 73

True

Front 74

Breaks in the DNA facilitate what?

Back 74

the initiation of recombination

Front 75

What can a defect in the DNA ligase cause?

Back 75

abmormal amounts of recombination

DNA ligase affects joining together of adjacent segments of DNA on a chromosome

Front 76

Recombination

Back 76

the reciprocal exchange of genetic information

Front 77

Recombination can be the result of what 4 things?

Back 77

1. reciprocal exchange during cell division
2. DNA damage (x ray)
3. Introduction of foreign DNA
4. Programmed recombination during the development or maturation of a cell (ex: antibody producting genes during B-cell maturation)

Front 78

What is gene conversion?

Back 78

the non-reciprocal exchange of genetic information

Front 79

Recombination between direct repeated sequences on the same chromosome causes what?

Back 79

the loss of DNA that was between the two repeated segments

Front 80

How can circular DNA be inserted in a chromosome?

Back 80

by recombination between a region of a circular molecule and a homologous region on the chromosome

Front 81

T/F Transposable elements are found only in bacteria

Back 81

False, they are found in all species from bateria to human

Front 82

What do transposable elements do?

Back 82

They can move from one location in DNA to another within that cell. They can cause changes in the DNA at the site of insertion

Front 83

Describe the 2 major types of transposable elements

Back 83

1. Contains inverted repeated sequences at the ends and causes a short region of the genome to be duplicated at the site of insertion
2. structuraly similar to a retrovirus and transposes through an RNA intermediate

Front 84

What is unequal crossing over?

Back 84

recombination that resulted from imprecise pairing of tandemly repeated sequences

Front 85

What is the result of unequal crossing over?

Back 85

the loss or gain of gene copies

Front 86

What are the two type of mutations?

Back 86

1. DNA rearrangments
2. base substitutions

Front 87

T/F There are many mechanisms in each cell for repairing DNA

Back 87

True

Front 88

What can happen from damage to a nucleotide?

Back 88

it can either be repaird or lead to a permanent mutation

Front 89

What are 2 things that can cause mutations?

Back 89

1. errors during replication
2. injury to the DNA from chemicals or radiation

Front 90

What can be used to detect specific bacterial species in the oral cavity using PCR?

Back 90

species specific primers

Front 91

Can many of trhe bacteria detected by PCR be easily cultured?

Back 91

no

Front 92

T/F Many of the bacteria in the oral cavity are present in small amounts

Back 92

True

Front 93

A small fraction of every genome is made up of what?

Back 93

segmental duplications or large regions of DNA that are present in more than one copy

Front 94

how is the duplicated DNA is generated?

Back 94

gene amplification

Front 95

What can gene amplification result in?

Back 95

The resistance to drugs, transformation into cancerous cells, or other changes in cell phenotype

Front 96

Several human diseases are du to what?

Back 96

defects in DNA repair enzymes