quiz #3

The nucleotide is the… of DNA

building block

the 2 strands are joined by nitrogenous pairs with a … bond in-between and are …

hydrogen; antiparallel

one strand can be the

template to another

the carbons in the sugar molecule of RNA and DNA are

numbered clockwise

DNA replication is

semi conservative

the requirements for DNA replication are

enzymes, DNA template, and A,T,C,G (dNTP’s)

the strand of DNA starts with… phosphate and after a nucleotide is attached, we lose … phosphate

3; 2

the energy released from releasing 2 phosphate goes to

anabolic synthesis of DNA

the DNA strands separate at 

the origin of replication (ori)

prokaryotes have.. while eukaryotes have 

1 ori; multiple 

a replication bubble Is formed with

replication forks

helicase

the “ zipper “ at either side of the forks separating the DNA double helix

gyrase

prevents the supercoiling that happens when helicase unzips the strands

primase

synthesizes a primer

primer

a short piece of RNA that acts like a starting point for the next enzyme: DNA polymerase ii ( tells it where to go)

DNA polymerase synthesizes

a new DNA strand that is complementary to the DNA template

DNA polymerase can only add nucleotides to the … and that’s why DNA replication happens from 

3’ end of a preexisting nucleotide ; 5’ to 3’ end he t

the leading strand is built

continuously

continuous replication doesn’t have a

start and stop

lagging strand is built

away ( discontinuous ) from the replication fork

discontinuous replication 

starts and stops 

lagging strand requires

multiple RNA primers

Okazaki fragments

little fragments of lagging strand

DNA polymerase I

removes the RNA primers and replaces that with nucleotide

DNA ligase forms 

a bond between the fragments to seal them together 

DNA is … and its replication bubble has … each side unzipping

bidirectional; 2 forks ; towards each fork

central dogma of genetics

all living things do things the same way

a gene is

a segment of DNA that codes for a specific product

the final product of RNA is 

protein 

some DNA produce

tRNA and rRNA

the gene has three parts

promoter - start of the gene

coding region - the part of the gene that contains the code ( copied during transcription)

termination : stop signal

transcription is 

production of a complementary RNA copy from DNA template

transcription is carried out by

DNA polymerase

the steps of transcription is

initiation, elongation, and termination

initiation is when

RNA polymerase binds to the promotor part of the gene and a bubble forms over it

elongation is when 

the RNA polymerase moves along the DNA and makes each nucleotides complimentary copy from the template strand

elongation’s RNA synthesis

goes from 5’ to 3’

termination is when

the RNA polymerase reaches the terminator and transcription stops

the three types of RNA are

mRNA , tRNA , and rRNA

translation is 

a protein synthesis

the requirements for something to be considered translation

has codons ( 3 mRNA nucleotides that code for one amino acid)

translation has something called a anticodon,

3 tRNA nucleotides that are complementary to one specific codon (UGG - ACC)

ribosomes are made of… and have .. components

proteins and rRNA ; 2 (subunits)

the ribosome has 3 sites for tRNA

P site, A site , and E site

the steps of translation are

initiation, elongation, and termination

translation initiation is when

a ribosome attaches to AUG ( the start codon) and tRNA brings methionine to the P site

elongation is when

a tRNA brings its amino acid to the A site ( codon recognition), a peptide bond forms, the ribosome moves down and the tRNA that was in the P site moves down to the E site and exits while the tRNA that was in A site moves down to P site and so forth

translation termination is when

a stop codon enters the A site and everything stops

in prokaryotes, translation and transcription happen .. because they lack a ..

at the same time ; nucleus

therefore, prokaryotes do their translation and transcription in the

cytoplasm

as for eukaryotes, translation and transcription happen in … and therefore happen at 

different places (cytoplasm and nucleus); different times 

bacteria only express genes that are

necessary for maximum growth under certain environmental conditions

gene expression means the gene

has been translated and transcribed

Organisms can control which genes are being expressed

at both the transcription and translation stages

inducible operon 

are not needed all the time but certain situations need it

an operon is

multiple genes that share a common promoter

the genes in

the operon share a common function such as lac operon who shares 3 genes that all help in metabolizing lactose

the lac operon is found in .. and has 3 genes called …. that help in … and have a 

E. coli ; lac z, lac y, and lac a; metabolizing lactose; promoter

near lac operon is a gene called.. that produces a …

lac L; repressor protein that represses transcription

The lac operon is

inducible ( not always needed but always there) because if there is no lactose around why stay turned on and it turns on in the presence of lactose

if lactose was absent in the environment,

the repressor gene would bind to the operator or the lac operon

by binding, the repressor gene prevents

the RNA polymerase from reaching the coding region

if lactose was present in the environment, 

the cell converts some of the lactose into a similar chemical called allolactose

allolactose is the

inducer and it stimulates transcription.

allolactose also

binds to the repressor protein and causes conformational change inactivating the repressor which then triggers transcription to start since the inactive repressor bound to the operator

what is evolution? 

change to nucleotide sequence of DNA lead to phenotypic changes within a population over time

…. evolve not people

populations 

the smallest unit that can evolve is a …

population

even though population is the smallest unit of survival, what can affect the evolution of the population?

the survival and reproduction of individuals

what is the raw material for evolution?

mutation

populations cannot change unless there is what?

genetic diversity

the ultimate cause of all genetic diversity is what?

mutation

some of the effects of mutation are … most are … a few are

neutral ( neither harm or help); harmful; harmless

fitness means

reproductive potential 

by reproductive potential, it basically means the 

ability to survive under current environmental  conditions which allows a greater amount of offspring to be produced before the death of the organism.

by being high fitness, you automatically…

out reproduce and out live those with low fitness

the expectation is that genes that give high fitness will what?

increase within the population over time

the environments are always changing so a characteristic that may be considered high fitness now,

may turn to low fitness ( global warming )

horizontal transfer Is ..

the transfer of DNA between 2 cells of the same generation

horizontal transfer is different from vertical transfer which is

the transfer of DNA from parent to offspring

the 3 types of horizontal transfer are 

transformation, conjugation, and transduction

transformation is ..

the uptake of DNA from the external environment

Naked DNA is DNA that isn’t

surrounded by a cell

when a bacterial cell lyse’s ( explodes), the DNA is

released from the cell into the environment

Because of the cell lysing, the DNA is

present in chromosomal fragments

competence is the 

ability to carry out transformation

only certain genes are

naturally competent

cells aren’t competent all the time, but become competent from

stress like starvation for example