BIOL Exam 3

Question 1

Choose which of the following is true:
a) Haploid cells have one allele per gene
b)Haploid cells have two alleles per gene
2. Diploid = 2,n with n being # of chromosomes so,
a) Haploid = n
b)Haploid = 3n
3. Fill in the numbers: Humans = ____,_____. Fruit flies, who
have 4 chromosomes and are diploid = _____,_______.
Haploid cells have one copy
of each chromosome
Diploid cells have two copies

Answer 1

1) A
2) A
3) 2,23 - 2,4

Question 2

meiosis I

Answer 2

separates homologous chromosomes while replicated sister chromatids stay together in the two daughter cells

Question 3

meiosis II

Answer 3

the two daughter cells divide again to separate the sister chromatids into two additional daughter cells each

Question 4

nondisjunction

Answer 4

chromosomes fail to separate after crossover so they segregate together - incorrect number of chromosomes

Question 5

why does incidence of trisomy increase with maternal age?

Answer 5

egg production begins when a female is an embryo, germ cells begin to undergo meiosis to produce eggs but meiosis pauses in prophase I (during crossing over) until sexual maturity

Question 6

outcrossing

Answer 6

when gametes from different individuals combine to form offspring - most genetic variety you can get

Question 7

self-fertilization

Answer 7

when two gametes produced by the same individual fuse to form a diploid offspring - sexual reproduction

Question 8

start codon

Answer 8

AUG - signals that protein synthesis whould begin - specifies the amino acid methionine

Question 9

Which codon in this mRNA specifies the
third amino acid in the resulting protein?
5’ UGCAUGCCCGCUUAAGAC 3’
a) CCC
b) GCU
c) UAA
d) UCG

Answer 9

B

Question 10

all amino acids except methionine and tryptophan are coded for by ____ one codon

Answer 10

more than

Question 11

A codon ___ codes for more than one amino acid

Answer 11

never

Question 12

when several codons specify the same amino acids, the first two bases are usually ___

Answer 12

identical

Question 13

point mutation

Answer 13

alters one or a small number of bases

Question 14

chromosomal mutation

Answer 14

alters a large segment of dna

Question 15

silent point mutation

Answer 15

base pair change doesn’t effect the mRNA - doesn’t change the amino acid, so there is no effect

Question 16

nonsense point mutation

Answer 16

premature stop codon - makes protein too short to function

Question 17

conservative missense mutation

Answer 17

you have a point mutation where you bring in a different amino acid - but they are same category (ex lys and arg) so they behave similarly - mild effect

Question 18

non conservative missense mutation

Answer 18

you have a point mutation where you bring in a different amino acid - different category of amino acids w/ diff properties so has a severe effect

Answer 19

1. Acidic, No effect
2. Acidic, Mild Effect
3. Nonpolar, Severe Effect
4. Severe Effect

Question 20

three components of a gene

Answer 20

promotor
coding region
termination signal

Question 21

termination signal is ___ of the coding region. The promoter is ___ of the coding region

Answer 21

downstream, upstream

Question 22

sigma

Answer 22

transcription factor that binds to the RNA polymerase, guides it to the promotors and helps it to recognize -10 box and -35

Question 23

-10 box is ____ from +1. -35 is ___ from +1.

Answer 23

10 nucleotides upstream, 35 nucleotides upstream

Question 24

How would a mutation in a bacterial cell that deletes 3 nucleotides that
are 10 nucleotides upstream from the transcription start site affect
transcription?

Answer 24

Sigma wouldn’t detect the critical region and RNA wouldn’t begin transcription because the -10 distance would be different

Question 25

How would a point mutation 20 nucleotides upstream from the transcription start site affect transcription?

Answer 25

There would be no effect on transcription ;because the distances would still be maintained and sigma could recognize the critical areas of the promoter

Question 26

1. What happens when Estrogen is a lipid soluble signal. Where is its receptor located? On or inside the uterine cell membrane? 2. Estrogen binds to the estrogen receptor, activating it. The estrogen receptor binds to the promoter region of genes that cause uterine cell division. Which molecule is the transcription factor? 3. Binding of the transcription factor directly initiates what process? Transcription or translation? 4. Ultimately, what kind of proteins would you expect to be produced as a result of the transcription factor binding? (Think control of the cell cycle)

Answer 26

1. Inside the cell membrane 2. Estrogen Receptor 3. Transcription 4. Cyclins?

Question 27

How does transcription stop?

Answer 27

the termination signal is transcribed

Question 28

what is produced from transcription in eukaryotes?

Answer 28

pre-mRNA

Question 29

In eukaryotes, genes that need to be regulated together are bound by the same transcription factor that recognizes the same sequence. Therefore, genes that need to be regulated together have the same (select all) a) Promoter proximal element sequence b) Enhancer sequence c) Coding sequence

Answer 29

a, b

Question 30

in eukaryotes, different genes that need to be turned on at the same time will be bound by ____ so their ____ will be the same

Answer 30

the same transcription factor, regulatory sequences

Question 31

alternative splicing

Answer 31

Different length mRNA with diff combinations of exons so you can get different versions of the same protein from one gene

Question 32

prokaryotes - C & L in cytoplasm eukaryotes - C in nucleus, L in cytoplasm

Question 33

In prokaryotes, transcription and translation can occur nearly simultaneously. In eukaryotes, transcription and translation can never occur simultaneously. a) True b) False

Answer 33

True

Question 34

The first aminoacyl tRNA to bind (to the start codon in) the mRNA will always be carrying which amino acid? And what will be the anticodon on that first aminoacyl tRNA?

Answer 34

Thymin

Question 35

Ribosomes contain about equal amounts of protein and RNA and both can catalyze reactions. Investigating which location in the ribosome would provide an answer? a) Active site b) E, P and A spots c) Space between large and small subunit, where the mRNA is held

Answer 35

A

Question 36

For each statement, choose mRNA and/or tRNA and/or rRNA 1. A brain cell and a liver cell would have the same sequence of: 2. Translated into a protein: 3. Required for the process of translation: 4. Transports amino acids: 5. Catalyzes the peptide bond between amino acids:

Answer 36

1. rRNA & tRNA 2. mRNA 3.mRNA, tRNA, rRNA 4. tRNA 5. rRNA

Question 37

rRNA

Answer 37

RNA that composes the ribosome

Question 38

mRNA

Answer 38

messenger RNA

Question 39

tRNA

Answer 39

transfer RNA

Question 40

For example, a scientist wants to better understand the effect of a particular gene. She introduces a strand of RNA that is complementary to the target gene mRNA. What will happen? a) The target gene will not be expressed b) The target gene will be over-expressed

Answer 40

a

Question 41

DNA --> pre mRNA --> mature mRNA --> a.a. chain --> protein

Question 42

folding

Answer 42

proteins can fold spontaneously, or the process can be guided by the molecular chaperone proteins in the RER

Question 43

chemical modifications

Answer 43

carbs and other molecules get added in the RER

Question 44

amino acids removed

Answer 44

sometimes amino acids are chopped off a protein (in the GA or cytoplasm)

Question 45

Think about all the levels of gene expression control... 1. Which control mechanism is most energy efficient? 2. Which control mechanism allows for most rapid response to change in environmental conditions? a) Transcriptional control b) Translational control c) Post translation control

Answer 45

1. A - if you stop transcription at the higher level, you save energy because you don't have to do all of these processes 2. C

Question 46

hox genes

Answer 46

encode transcription factors - a single one can turn on a slew of developmental genes

Question 47

hox genes ____ of development genes by ______ in specific locations of a developing embryo

Answer 47

regulate the expression; turning them on and off

Question 48

In Drosophila, the hox gene lab is expressed only in the anterior cells of the developing fly embryo. When lab is artificially turned off or mutated, the embryo fails to develop the salivary glands, mandibles and pharynx. Which of the following is true of lab. (choose all) a) lab’s protein product normally turns on the genes related to mouth parts. b) lab’s protein product normally forms the mouth. c) lab only exists in the DNA of the anterior cells. d) lab exists in the DNA of all cells but is only expressed in the anterior cells.

Answer 48

a, d

Question 49

The hox gene antp in Drosophila is normally expressed in the second segment of the fly’s thorax during embryonic development. antp tells other genes to “build legs here!” If antp is mutated such that it is expressed in the thorax but also the head, where will the legs grow?

Answer 49

the head as well as the thorax

Question 50

So, how did limbs disappear in snakes? Use the following information to formulate a hypothesis. In chickens, where hoxc6 is expressed by itself, the forelimb forms. Where hoxc6 and hoxc8 are expressed together, ribs form. In snakes, hoxc6 and hoxc8 are always expressed together.

Answer 50

hoxc8 didn't shut off when it should have, so limbs didn't grow (only ribs)

Question 51

transcription

Answer 51

genes are transcribed to mRNA by RNA polymerase

Question 52

how does transcription occur?

Answer 52

RNA polymerase binds to the 3' end of the template strand and synthesizes complementary in the 5' to 3' direction

Question 53

when else do we see a non-Mendelian pattern of inheritance? a) When genes are located on different chromosomes b) When genes are located far away on the same chromosome c) When genes are located close together on the same chromosome

Answer 53

C - crossing over doesn't (ineffective)

Question 54

linkage

Answer 54

the tendency of alleles from different genes to be inherited together because they are located close to each other on the same gene

Question 55

translation

Answer 55

ribosome binds to mRNA and recruits correct amino acids to make a protein

Question 56

the central dogma

Answer 56

flow of information via transcription and translation

Question 57

codons

Answer 57

three bases at a time - each specifies an amino acid

Question 58

when a ribosome reads mRNA, it reads ____, called ____

Answer 58

three bases at a time; codon

Question 59

what is the start codon for all amino acids

Answer 59

AUG (methionine)

Question 60

what are the three stop codons?

Answer 60

UAA, UAG, UGA

Question 61

Stop codons Do/Do not code for an amino acid

Answer 61

Do not

Question 62

which amino acids only have one codon?

Answer 62

tryptophan and methionine

Question 63

splicesosome

Answer 63

composed of lots of small nuclear ribonucleoproteins (snRNPs) = RNAs + proteins

Question 64

what happens when the gene talpid2 is mutated in birds?

Answer 64

the chicken embryos grow teeth until gestation day 18, and then they died

Question 65

Why do human hands start off webbed? Why do human embryos have tails and gill slits?

Answer 65

humans inherited the genes for these traits from fish ancestor, they turned off but didn't disappear

Question 66

hox genes are conserved/not conserved among animal species

Answer 66

conserved - very similar in animals and are in a matching pattern

Question 67

The mouse hox gene, pb, controls eye development and is normally expressed in the mouse face. Scientists inserted pb into a developing fruit fly embryo. They forced pb to be expressed in the back leg region of the fly embryo. * What do you think happened? a) A fly eye developed in the fly back legs b) A mouse eye developed in the fly back legs c) A mouse eye developed in the fly head

Answer 67

A

Question 68

2. DNA analysis used for identifying paternity involves looking at which type of DNA? c) Protein coding regions of DNA d) non protein coding regions of the DNA

Answer 68

D

Question 69

In which type of DNA is there more variation (differences) between Greg and Henry (or any two individuals)? a) Protein coding regions of DNA b) Non protein coding regions of DNA

Answer 69

B

Question 70

Short Tandem Repeats or microsatelllites

Answer 70

common genetic marker for identifying individuals - short DNA sequences that repeats over and over again but varies in repeat number

Question 71

genetic markers

Answer 71

variable regions of the genome that have a known location used to differentiate individuals

Question 72

Step 1 to identify paternity

Answer 72

take DNA sample from baby, mom, and two parents

Question 73

Step 2 to identify paternity

Answer 73

Add the samples to the PCY - makes many copies of the DNA region (in this case an STR)

Question 74

STEP 3: Add the “ingredients” which allows PCR to amplify the gene. What enzymes/molecules need to be added for PCR to replicate the gene of interest? Select all a) RNA polymerase b) DNA polymerase c) Primers d) Ribosomes e) Amino acids

Answer 74

B, C

Question 75

which natural process is emulated by polymerase chain reaction?

Answer 75

DNA replication

Question 76

how do molecules move through gel electrophoresis?

Answer 76

from the negative to the positive end of the gel; smaller molecules move faster & farther

Question 77

intron

Answer 77

regions of pre-mRNA that do not code for a protein

Question 78

exons

Answer 78

regions of pre-mRNA that code for a protein

Question 79

what is the point of transcription?

Answer 79

to make an mRNA

Question 80

how does a termination signal stop RNA polymerase

Answer 80

contains Cs and Gs that form a hairpin and physically separates the RNA polymerase from the RNA

Question 81

mRNA processing in eukaryotes

Answer 81

the mRNA from transcription is pre-mRNA and must be processed (splicing)

Question 82

what happens during the process of splicing?

Answer 82

introns are moved and exons are bonded (spliced) together

Question 83

where do transcription and splicing occur?

Answer 83

the nucleus

Question 84

gene expression

Answer 84

cells control which genes are transcribed at which times - cells respond to changes In environment and have a unique identity

Question 85

positive control

Answer 85

when regulatory molecule facilitates transcription

Question 86

negative control

Answer 86

when regulatory molecule stops transcription

Question 87

operon

Answer 87

units in prokaryotes that contain all the genes that function in a related way together in the same region of their chromosome and are all controlled with the same promoter

Question 88

why don't we get a lot of gene expression in more condensed chromatin?

Answer 88

RNA polymerase doesn't have exposed DNA to attach to

Question 89

condensed chromatin is ____ based, which means ____ enzymes add ____ to _____

Answer 89

methylation; DNA methyltransferase; methyl groups; DNA

Question 90

DEcondensed chromatin is ____ based, which means ____ enzymes add ____ to _____

Answer 90

acetylation; histone acetyltransferase; acetyl groups; histones

Question 91

what do CAS1 CAS2 do?

Answer 91

take a "picture" to remember the virus invading the cell

Question 92

gRNA

Answer 92

guide RNA - complementary to the gene of interest (you want to fix)

Question 93

What part of the naturally occurring CRISPR system does the engineered gRNA mimic? a) Like the CRISPR mRNA, it guides the cas9 to the invading virus b) Like CAS, it copies a sequence form the invading virus c) Like CAS9, it chops up the invading virus d) Like, RNA polymerase, it transcribes the CRISPR mRNA

Answer 93

A

Question 94

so if this is in a bacteria then how is it working in humans?