unit 6: gene expression and regulation

Question 1

transformation

Answer 1

the process by which a cell in culture acquires the ability to divide indefinitely.

Question 2

chargaff’s rules

Answer 2

-DNA base composition varies between species
-percentages of Adenine-thymine and cytosine-guanine will be roughly equal

Question 3

three components of a nucleotide

Answer 3

-sugar molecule
-phosphate group
-nitrogenous base (adenine, thymine, cytosine, guanine)

Question 4

Who built the first model of DNA and shared the 1962 Nobel Prize for discovery of its structure?

Answer 4

Rosalind Franklin obtained images of DNA using X-ray crystallography, an idea first broached by Maurice Wilkins. These images allowed James Watson and Francis Crick to create the double-helix model. Watson and Crick built the model and wrote a one pager report. Maurice Wilkins joined them in receiving the Nobel Prize.

Question 5

Purines

Answer 5

adenine and guanine

Question 6

pyrimidines

Answer 6

thymine and cytosine and uracil

Question 7

leading strand

Answer 7

the new complementary DNA strand synthesized continuously along the template strand towards the replication fork in the mandatory 5’—3’ direction

Question 8

lagging strand

Answer 8

Lagging strand is synthesized discontinuously, as a series of segments. The segments of the lagging strand are called Okazaki fragments. synthesized in a 5’—3’ direction away from the replication fork

Question 9

helicase…

Answer 9

untwists and separates strands, holds DNA strands apart

Question 10

primase…

Answer 10

synthesizes RNA primer

Question 11

DNA polymerases

Answer 11

adds DNA nucleotides to new strand,

Question 12

DNA polymerase I

Answer 12

removes RNA primer and replaces it with DNA nucleotide bases

Catalyzes the elongation of new DNA (ex. At a replication fork) by adding nucleotides to the 3’ end of an existing chain.

Question 13

DNA ligase

Answer 13

joins DNA (Okazaki) fragments together

Question 14

topoisomerase

Answer 14

relieves strain caused by unwinding of strands. breaks swivels and rejoins the parental DNA ahead of the replication fork.

Question 15

what is gene expression

Answer 15

The process by which DNA directs the synthesis of proteins (or just RNAS) includes two stages: transcription and translation

Question 16

5’ cap and poly-A tail functions

Answer 16

They facilitate the export of the mature mRNA from the nucleus.
They help protect the mRNA from degradation by hydrolytic enzymes
They help ribosomes attach to the 5’ end of the mRNA once the mRNA reaches cytoplasm.

Question 17

introns

Answer 17

Introns: non-coding sequences present in the DNA; removed by RNA splicing before translation

Question 18

exons

Answer 18

nucleic acid coding sequences, present in mRNA

Question 19

mRNA

Answer 19

carries a genetic message from the DNA to the protein-synthesizing machinery of the cell. Attaches ribosomes in the cytoplasm and specifies the primary structure of a protein

Question 20

tRNA

Answer 20

serves as a link between mRNA molecule and growing chain of amino acids. Helps decode an mRNA sequence into a protein

Question 21

rRNA

Answer 21

part of the ribosome of the cell. responsible for reading the order of amino acids together. Non-Coding RNA component of ribosomes, carries out protein synthesis in ribosomes

Question 22

anticodon

Answer 22

A nucleotide triplet at one end of a tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule

Question 23

mutation

Answer 23

change in the nucleotide sequence of an organism’s DNA or in the DNA or RNA of a virus

Question 24

point mutation

Answer 24

a change in a single nucleotide pair of a gene

Question 25

frameshift mutations

Answer 25

A mutation occurring when nucleotides are inserted in or deleted from a gene and the number inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.

Question 26

nonsense vs. missense mutation

Answer 26

Nonsense: A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein. Missense: a nucleotide pair substitution that results in a codon that codes for a different amino acid. Substitution that changes one amino acid to another.

Question 27

promoter

Answer 27

a site where RNA polymerase can bind to DNA and begin transcription

Question 28

operator

Answer 28

Switches on/off the metabolic pathway. In bacterial and phage DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach. The binding of the repressor prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon. The operator is the "on switch" for gene regulation. it is positioned within the promoter or between the promoter

Question 29

operon

Answer 29

The entre stretch of DNA required for enzyme production for the pathway. The operator, promoter and genes they control

Question 30

How does a repressor protein work?

Answer 30

It binds to the operator and blocs attachment of RNA polymerase to the promoter, preventing the transcription of the genes. Specific to the operator of a particular operon

Question 31

regulatory gene

Answer 31

A gene that codes for a protein, such as a repressor, tht controls the transcription of another gene or group of genes. Expressed continuously, although at a low rate.

Question 32

Distinguish between inducible and repressible operons and describe one example of each type.

Answer 32

A trp operon is said to be repressible operon because its transcription is usually on bu can be inhibited (repressed) when a specific small molecule (in this case, tryptophan) binds allosterically to regulatory protein. An inducible operon is usually off but can be stimulated (induced) to be on when a specific small molecule interacts with a different regulatory protein (ex. Lactose operon)

Question 33

cell differentiation vs morphogenesis

Answer 33

Cell differentiation is when specialized structures and functions are achieved. Morphogenesis is the arrangement of cells to make organs/shapes

Question 34

gel electrophoresis

Answer 34

a technique used to separate nucleic acids or proteins that differ in size or electrical charge. a laboratory method used to separate mixtures of DNA, RNA, or proteins according to molecular size. In gel electrophoresis, the molecules to be separated are pushed by an electrical field through a gel that contains small pores.

Question 35

DNA microarrays assays

Answer 35

DNA microarray assays: consist of tiny amounts of a large number of single-stranded DNA fragments representing different genes fixed to a glass slide in a tightly spaced array of dots. Ideally, these fragments represent all the genes of an organism. The resulting pattern of colored dots after the addition of fluorescent labels and mRNAs reverse transcribed into complementary DNAs, reveals the dots to which each probe was bound and thus the genes that are expressed in the cell samples being tested.

Question 36

bioinformatics

Answer 36

the use of computers, software, and mathematical models to process and integrate biological information from large data sets.

Question 37

proteomics

Answer 37

systematic study of sets of proteins and their properties, including their abundance, chemical modifications and interactions