Ch.8

Question 1

Genetics

Answer 1

study of what gene are, how they carry information, how info is expressed and how genes are replicated

Question 2

Gene

Answer 2

a segment of DNA that encodes a functional product, usually a protein

Question 3

Chromosome

Answer 3

structure containing DNA and the genes

Question 4

Genome

Answer 4

all the genetic information in a cell

Question 5

Genomics

Answer 5

molecular study of genomes

Question 6

Genotype

Answer 6

the genes of an organism

Question 7

Phenotype

Answer 7

expression of genes

Question 8

Expression

Answer 8

genetic info is used within a cell to produced proteins needed

Question 9

Recombination

Answer 9

genetic information can be transferred horizontally between cells of the same generation

Question 10

Replication

Answer 10

genetic information can be transferred vertically to the next generation of cells

Question 11

Adenine

Answer 11

combines with Thymine

Question 12

Guanine

Answer 12

combines with Cytosine

Question 13

Cytosine

Answer 13

combines with Guanin

Question 14

Thymine

Answer 14

combines with Adenine

Question 15

Dna Synthesis Occurs

Answer 15

At the 5 prime to 3 prime direction , started by RNA primers that make chunks of 5-10 strands, then DNA polymerase takes that and builds for it , the leading strand is made continuously because it can only add at the 3 prime end and it needs to maintain the structure because of this the lagging strand is made in pieces (okazaki fragments) because it is being made from the 3 to 5 . It has to keep the antiparallel structure A hydroxyl group is needed at te 3 prime position in order to build .
It is built in the 5 to 3 prime direction, and read in the 3 to 5 prime direction (template) in order to keep the anit parallel nature of the duplex
Called the trombone model

Question 16

Dna replication process consists of

Answer 16

Replication enzymes break weak hydrogen bonds between nucleotides and the double helix separates
Hydrogen bonds form between new complementary nucleotides
Enzymes then catalyze the formation of sugar-phosphate bonds between sequential nucleotides on each resulting daughter strand

Question 17

nucleotide

Answer 17

A nucleoside triphosphate bonds to sugar and loses two phosphate, the hydrolysis of the phosphate bonds gives energy to the reaction

Question 18

DNA Gyrase

Answer 18

enzyme that relaxes tension ahead of the replication fork

Question 19

DNA Ligase

Answer 19

makes covalent bonds to DNA strands, joins Okazaki fragments and new segments in excision repair

Question 20

DNA polymerase

Answer 20

Synthesizes DNA, proofreads and repairs DNA , copies DNA

Question 21

Helicase

Answer 21

unwinds double stranded DNA , opens up the structure to begin with

Question 22

RNA Primase

Answer 22

an RNA polymerase that makes RNA primers from a DNA template , the helpers of dna polymerase

Question 23

Topoisomerase

Answer 23

also Relaxes supercoiling ahead the replication for, separates DNA circles at the end of the DNA replication

Question 24

So how does the trombone model work with all these enzymes

Answer 24

So essentially Helicase and other enzymes unwind the double helix while proteins stabilize the unwound dna, the leading strand is synthesized by DNA Polymerase with the help of RNA primers, DNA ligase joins the okazaki fragments in the lagging strand. DNA gyrase and topoisomerase ease tension ahead of the replication fork before it unwinds.

Question 25

Dna replication is circular and happens in two directions , what is this called?

Answer 25

bidirectional replication

Question 26

Codon

Answer 26

a set of 3 nucleotides in mRNA that codes for an amino acid or stop signal Starts at the start codon AUG (codes for amino acids) and ends at nonsense codons, UAA, UAG, UGA

Question 27

How many codons in mRNA and how many amino acids

Answer 27

61 sense codons, 20 amino acids , 3 codons are nonsense codons (stop signals)

Question 28

What does it mean to say that the genetic code is degerate?

Answer 28

because some amino acids have more than one codon

Question 29

polyribosome

Answer 29

Rna+ ribosome

Question 30

Constitutive genes

Answer 30

are expressed at a fixed rate, like the genes involved in Glycolysis Other genes are expressed only as needed

Question 31

Inducible genes

Answer 31

are off and must be on

Question 32

Repressible genes

Answer 32

on and must be turned off

Question 33

Catabolite repression aka Glucose effect

Answer 33

inhibition of alt carbon sources by glucose , no glucose? Lag time for genes to turn off for lactose to be used instead Graph showing e coli grows fast on glucose, but will use lactose if needed at the cost of longer spawn time

Question 34

Mutation

Answer 34

alteration of nucleotide sequences, can happen spontaneously or in the presence of mutages, base changes additions, or deletions are different types

Question 35

Mutagen

Answer 35

is an agent that causes mutations increases rate to 10^-5 or 10^-2 per replicated gene ie 10 to 1000x

Question 36

Spontaneous mutation

Answer 36

occurs in the absence of a mutagen 1 in 10^9 for replicated base pairs or 1 in 10^6 for replicated genes

Question 37

Point mutation/base substitution

Answer 37

change in one base

Question 38

Missense mutation

Answer 38

consequence of a point mutation result in change of an amino acid

Question 39

Nonsense Mutation

Answer 39

consequence of a point mutation where it results in a nonsense codon (stop codon)

Question 40

Frame mutation

Answer 40

insertion or deletion of one or more nucleotides pairs causing a shift in the reading frame, bigger chance of something serious happening

Question 41

Radiation

Answer 41

causes formation of ions that can mess with nucleotides and deoxyribose phosphate backbone

Question 42

Uv radiation

Answer 42

causes thymine dimers (lesoins in the DNA) So repair comes in, photolysis separate thymine dimers caused by UV radiation There is also nucleotide excision repair

Question 43

Vertical gene transfer

Answer 43

occurs during reproduction between generation of cells

Question 44

Horizontal gene transfer

Answer 44

the transfer of genes between cells of same gen

Question 45

Genetic recombination

Answer 45

Exchange of genes between two DNA molecules occurs when two chromosomes break and rejoin Donor DNA → Receipts Species that can do this are competent Naked dna

Question 46

conjugation

Answer 46

A plasmid is sent from a donor F+ to recipient F-, the F- is converted to an F+ cell,, through the mating bridge or sex pilus

Question 47

plasmid

Answer 47

a small circular piece of DNA found in bacterial cells

Question 48

bacterialphage

Answer 48

Another way that it can be done is via bacterial viruses called bacterialphage Phage DNA can combine to the host cell DNA this is transduction

Question 49

specific transduction

Answer 49

Viruses can specify which gene they want to change

Question 50

Transposons

Answer 50

segments of DNA that can move from one region to another , contain insertion sequences for cutting and resealing DNA