The Paradigm of Differential Gene Expression

Question 1

approximately how many protein encoding genes are present in humans?

Answer 1

25,000

Question 2

at what 4 steps can regulation occur for the selective expression of gene products?

Answer 2

1. differential gene transcription
2. selective nuclear RNA processing
3. selective mRNA translation
4. differential protein modification

Question 3

differential gene expression refers to

Answer 3

which genes are allowed to be transcribed within the nucleus

Question 4

selective nuclear RNA processing refers to

Answer 4

which transcribed RNA sequences will make it to the cytoplasm

Question 5

selective mRNA translation refers to

Answer 5

which mRNA is translated into proteins

Question 6

differential protein modification refers to the determination of

Answer 6

which proteins are activated/functional

Question 7

chromatin is a form of

Answer 7

DNA unique to eukaryotic cells

Question 8

is chromatin found in prokaryotic cells?

Answer 8

NO

Question 9

define nucleosome

Answer 9

basic unit of chromatin which contains the genetic information

Question 10

the nucleosome structure is comprised of

Answer 10

histone subunits

Question 11

the histone subunits of nucleosomes are encased with

Answer 11

2 bands of 147 DNA base pairs

Question 12

histones are

Answer 12

octamer protein subunits

Question 13

linker proteins contain _________ base pairs that link…

Answer 13

60-80

adjacent nucleosomes

Question 14

what is the primary type of histone bound to the linker section?

Answer 14

histone H1

Question 15

what prevents uncoiling of nucleosomes?

Answer 15

tightly joined nucleosomes linked together

Question 16

the tight linkage between nucleosomes allows for

Answer 16

polymerase enzymes to bind & transcription proceeds

Question 17

H1 represses or regulates the…

Answer 17

transcription of DNA to mRNA

Question 18

what prevents the uncoiling of nucleosomes and DNA?

Answer 18

acetylation of histones

Question 19

what represses or prevents the uncoiling of nucleosome units?

Answer 19

methylation

Question 20

define exons

Answer 20

regions of the DNA which code for a protein

Question 21

define introns

Answer 21

regions of DNA not expressed in the final amino acid sequence of a protein

Question 22

promotor sites are the binding location for

Answer 22

RNA polymerase enzymes on DNA

Question 23

promoter sites allow for transcription of

Answer 23

DNA to mRNA

Question 24

initial nuclear RNA consists of

Answer 24

• promotor site
• cap sequence
• tail sequence

Question 25

the cap sequence is found at what end of RNA?

Answer 25

5’

Question 26

poly A tail is found at the

Answer 26

3’ end of RNA

Question 27

enhancers are

Answer 27

DNA sequences which control the efficiency and rate of transcription from a promoter region

Question 28

negative enhancer prevent the

Answer 28

premature formation of proteins and cells

Question 29

negative enhancers can maintain the proper sequnce of

Answer 29

morphogenesis & organogenesis

Question 30

transcription factors bind to the

Answer 30

enhancer/promoter regions to activate/repress transcription of a gene

Question 31

transcription factors recruit

Answer 31

acetyl transferases

methyltransferases

Question 32

acetyl transferases loosen the…

methyltransferases tighten the

Answer 32

histones and nucleosomes for transcription to occur

histone complex to repress transcription

Question 33

transcription factors can form bridges to form a loop of DNA this causes

Answer 33

enhancer/promoter region to be closer together causing more efficient transcription

Question 34

why are totipotent stems cells still capable of forming all cell types?

Answer 34

ICM has not undergone methylation

Question 35

censorship refers to different cell types represented by the

Answer 35

processing of specific nuclear RNA transcripts into mRNA

Question 36

differential splicing leads to an

Answer 36

assortment of various combinations of exons

Question 37

due to differential splicing for humans one gene produces

Answer 37

multiple polypeptides or proteins

Question 38

due to differential splicing for prokaryotes one gene produces

Answer 38

only ONE polypeptide or protein

Question 39

what is the downside of having 1 gene producing many polypeptides?

Answer 39

a single gene mutation can lead to abnormalities of multiple proteins

Question 40

what are spliceosomes?

Answer 40

a modified form of RNA which binds to nRNA strand to excise and ligate

Question 41

spliceosomes are capable of

Answer 41

removing a mutated segment of RNA so transcription can proceed normally

Question 42

what protects the mRNA from rapid enzymatic degradation in the cytoplasm?

Answer 42

the poly-A-tail

Question 43

the maintenance and stabilization of the mRNA allows for more

Answer 43

efficient synthesis of its protein product

Question 44

an mRNA strand w/o a tail or cap would be

Answer 44

degraded before translation at ribosomes can occur

Question 45

the oocyte/egg stores some mRNAs that will be used ONLY

Answer 45

after fertilization

Question 46

the mRNAs stored in the oocyte code for proteins that are needed for

Answer 46

• cleavage
• actin and cytoskeleton strands
• cyclin proteins

Question 47

cyclin proteins are used to

Answer 47

regulate the timing of cell division

Question 48

a polypeptide is a

Answer 48

non-function protein precursor