Functional bio test 4

for transcription to occur RNA polymerase must bind to promotor.

-easier for RNA polymerase to get turned on on the decondensed side of the chromatin

the final mature mRNA has

-exons (the region that codes for the proteins), 5' cap, 3' poly (A) tail, 5' and 3' untranslated regions

2. termination of transcription:

-polyadenylation signal (polyA) -enzyme recognizes and cuts mRNA to free- transcription will be stopped

1 mRNA: 1 protein ratio:

1 RNA can lead to a large amount of protein. 1 mRNA can make lots of proteins

many protein chains can be made from

1 mRNA at the same tiem

after proof reading by DNA polymerase

1 mistake per 10 million nucleotides

initial base addition by DNA polymerase

1 mistake per thousand nucleotides

termination

1) In enzyme-catalyzed reactions, the finial stage in which the enzyme returns to its original conformation and products are released. (2) In transcription, the dissociation fo the RNA and RNA polymerase from DNA. (3) In translation, the release of the polypeptide and dissociation of a ribosome from mRNA when the ribosome reaches a stop codon.

initiation

1) in an enzyme-catalyzed reaction, the stage during which enzymes orient reactants precisely as the bind at specific locations within the enzymes active. (2) in DNA transcription, the stage during which RNA polymerase and other proteins assemble at the promoter sequence and open the strands of DNA to start transcriptions. (3) In translation the stage during which a complex consisting of initiation factor proteins, a ribosome, a mRNA, and an aminoacyl tRNA corresponding to the start codon is formed to being translation.

elongation

1)The process by which RNA lengthens during transcription. (2) The process by which a polypeptide chain lengthens during translation.

1. eukaryotic RNA polymerases:

1, 2, and 3 for different types of RNA. ***RNA polymerase 2 transcribes protein-coding genes

leading strand replication process

1. DNA helicase opens double helix at origin of rep 2. single strand binding proteins stabilize the single DNA strand 3. topoisomeraes relieves twisting forces4. RNA primase adds a small piece of RNA, RNA primer, to the DNA template (binds by complementary hydrogen bonding A-U, C-G) 5. DNA polymerase 3 adds nucleotides to RNA primer to build a new strand in a 5' to 3' direction

steps of elongation

1. Incoming aminoacyl tRNA -New tRNA moves into A site, where its anticodon bas pairs with the mRNA codon. 2. Peptide-bond formation-the amino acid attached to the tRNA in the P site is transferred to the amino acid of the tRNA in the A site. 3. Translocation-the ribosome moves one codon doen the mRNA with the help of elongation factors. The tRNA attached to thepolypeptide chain moves into the P site. The A site is empty. 4. Incoming aminoacyl tRNA -New tRNA moves into A site, where its anticodon base pairs with the mRNA codon. 5. Peptide-bond formation -The polypeptide chain attached to the tRNA in the Psite is transferred to the aminoacyl tRNA in the A site. 6. Translocation -The ribosome once again moves one codon down the mRNA. The tRNA attached to polypeptide chain moves into P site. Empty tRNA from P site moves E site, where tRNA is ejected. The A site is empty again

for lipid insoluble signals, signal must be processed

1. Signal cannot enter cell so the information is transduced (form is changed) inside the cell 2. The signal is then amplified for fast response 3. The intracellular signaling molecules then active regulatory transcription factors (and other proteins in the cell)

initiation process

1. mRNA binds to small subunit -A sequence in mRNA called the ribosome binding site binds to a complementarily sequence in an RNA molecule that is part of the small subunit of the ribosome, helped by initiating factors 2. Initiator aminoacyl tRNA binds to start codon 3. Large subunit of ribosome binds, Completing ribosome assembly. Translation can now begin.

events in initiation

1. mRNA binds to small subunit-A sequence in mRNA called the ribosome binding site binds to a complementarily sequence in an RNA molecule that is part of the small subunit of the ribosome, helped by initiating factors 2. Initiator aminoacyl tRNA binds to start codon 3. Large subunit of ribosome binds,Completing ribosome assembly. Translation can now begin.

how can we tell if a gene is being expressed or turned on?

1. production of RNA 2. production of a protein

RNA interference

1.transcription of genes that code for hairpin RNA 2. hairpin RNA transported to cytoplasm where the hairpin loop is cut out 3. one strand is taken up by the RNA-induced splicing complex (RISC)...now called a microRNA 4. microRNA binds to target mRNA 5. RISC cuts the mRNA and prevents translation. (translation will not occur)

each replication bubble has __ replication forks

2

The lagging strand of DNA is

3 prime to 5 prime.

DNA polymerae 3 an only attach nucleotides to the

3' end

In DNA replication, what direction is DNA read?in what direction is the new RNA strand made?

3' to 5' and 5' to 3'

how many bases specify the addition of a particular amino acid?

4 for 20 amino acids

o A two-base code could represent just

4x4, or 16, different amino acid

A three-base code could specify

4x4x4, or 64, different amino acids

The leading strand of DNA is

5 prime to 3 prime.

__ codons specify 20 amino acids

61

dispersive replication

A postulated mode of DNA replication combining aspects of conservative and semiconservative replication

How does the arrival of a termination codon at the A site trigger the end of protein synthesis?

A protein release factor binds in the A site and releases the polypeptide from the final tRNA to which it is bound.

Redundancy would mean that different codons in mRNA- say,

AAA and AAG might code for the same amino acid.

start site is the

AUG codon

Describe the structure and function of tRNAs in protein synthesis.

An L-shaped RNA molecule that has an anticodon at one end and an amino acid attachment site at the other. Each tRNA carries a specific amino acid and binds to the corresponding codon in messenger RNA during translation.

the role of RNA

An RNA molecule that forms part of the ribosome

frame shift mutation

An insertion or deletion of a base shifts the reading frame of the codons which changes sequence of amino acids.

elongation process

At the start of elongation, the E and A sites in the ribosome are empty of tRNAs. As a result, an mRNA codon is exposed in the A site. Elongation proceeds when and aminoacyl tRNA binds to the codon in the A site by complementary bas paring between the anticodon and codon. When both the P site and A site are occupied by tRNAs the amino acids on the tRNAs are in the ribosomes active site. This is where peptide-bond formation- the essence of protein synthesis- occurs. Peptide-bond formation is one of the most important reactions that take place in cells because manufacturing proteins is central to all cell processes.

deleterious mutations

Because most individuals tend to be well adapted to their current habitat, and because mutations are random changes in the genotype, many mutations lower fitness. These mutations are termed harmful or deleterious. The same G-to-A mutation that was beneficial in a beach habitat is deleterious In a mainland habitat. Note that whether a mutation is harmful or beneficial is not a property of the mutation alone- it depends on the environment.

missense mutation

Changes sequence of amino acids (replacement)

What kind of molecule is the "adapter" that couples amino acid sequences to the sequence of bases in the mRNA?

DNA

the secondary structure of DNA1

DNA is typically double-stranded with each strand consisting of a long, linear polymer made up of monomers called Deoxyribonucleotides. Each Deoxyribonucleotide consists of a deoxyribose sugar, a phosphate group, and a nitrogenous base. Deoxyribonucleotides link together into a polymer when a hydroxyl group on the 3' carbon of one deoxyribose and the phosphate group attached to the 5' carbon of another deoxyribose is joined by a covalent linkage called a phophodiester bond. The two strands combine together to make up one DNA molecule that functions as the genetic information storage molecule of cells. DNA's secondary structure is the double helix.

leading strand synthesis

DNA polymerase, the thing that is adding more and more nucleotides to grow the DNA, can only add nucleotides on the 3' prime end of a strand. Or, you can only extend DNA going from 5 prime to 3 prime. This works fine for the leading strand which follows this sequence. To start the process you need an RNA primer which is DNA primase, and then once there is a primer, then DNA polymerase can start adding nucleotides to the correct bases.

DNA polymerase 3 has proof reading ability to remove and correct mismatched bases during ___

DNA replication

the central dogma

DNA---> RNA-----> protein

silent mutation

Does not effect finial protein (often 3rd base of codon) least harmless

Describe mechanisms for correcting mistakes that occur in DNA synthesis during replication or repair.

During DNA replication, most DNA polymerases can "check their work" with each base that they add. This process is called proofreading. If the polymerase detects that a wrong (incorrectly paired)

cells that undergo gametes also go through interphase

G1, S phase, G2.

binds to the HER receptors and blocks

Herceptin

neutral chromosomal mutations

If a mutation has no effect on fitness, it is termed neutral. Silent mutations are usually neutral

Predict the outcome if cells that produce gametes did not express telomerase.

If cells could not express telomerase then the DNA strand would never be completed which would mean no life would happen.

How is a mutation in a bacterial cell that deletes three base pairs 10 base pairs upstream from the +1 site likely to affect transcription and why?

Initiation will be inhibited because sigma cannot bind to the promoter

basal transcription

Instead of using a sigma protein, eukaryotic RNA polymerases recognize promoters using a group of proteins. (any of class of proteins, present in all eukaryotic cells, that assemble on promoters and help initiate transcription)-. they assemble at the promoter, and RNA polymerase follows.

How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes?

It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity

What would be the consequence(s) for DNA synthesis if DNA ligase were defective?

Lagging strand synthesis would be incomplete; leading strand synthesis would be largely unaffected.

unambiguous

Never codes for more than one amino acid

non overlapping

Once the ribosome locks onto the first codon, the reading frame is established, and the ribosome then reads each separate codon one after another.

reverse transcription

RNA back to DNA

In the process of transcription, _____.

RNA is synthesized

what enzyme is used to undwind the DNA strands in transcription?

RNA polymerase

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?

RNA polymerase 1

nonsense mutation

Results in a STOP codon -shortened (truncated) protein

telomerase

Some cells have the ability to reverse telomere shortening by expressing ________, an enzyme that can make DNA using RNA as a template. -only active in fetal, developing, and tumor cells

beneficial chromosomal mutations

Some mutations increase the fitness of the organism- its ability to survive and reproduce- in a particular environment. The G-to-A missense mutation is beneficial in beach habitats because it camouflages mice

RNA can bind to ______ and other proteins will come with it initiating transcription

TATA box

Which sections in mature RNA do not code for amino acids?

The 3'cap and the poly(A) tail at the 5' end are part of mature RNA and do not code for amino acids.

messelson-stahl experiment

The Messelson-Stahl experiment was designed to determine whether DNA replication was conservative, semi-conservative, or dispersive. They chose to work with the organism E.Coli, same as in the Hershey and Chase experiment. Messelson and Stahl came up with a plan to grow the cells for successive generations in the presence of different isotopes of nitrogens. This difference in mass- which creates a difference in density was the key to the experiment. Messelson and Stahl showed that each strand of DNA is copied in its entirety each time replication occurs.

Discuss Cricks wobble hypothesis of tRNAs paring with >1 codon.

The hypothesis that some tRNA molecules can pair with more than one mRNA codon by tolerating particular types of nonstandard bas paring in the third base, so long as the first and second bases are correctly matched.

Which statement is correct concerning DNA synthesis catalyzed by DNA polymerases?

The new DNA strand is synthesized in the 5'—>3' direction; the template strand is read in the 3'—>5' direction.

What is the reaction catalyzed by aminoacyl-tRNA synthetases?

These enzymes catalyze formation of the bonds between the tRNA and the appropriate amino acids

In addition to splicing, additional modifications at the 5' and 3' end are required to generate a mature mRNA. What is the significance of these modifications?

These modifications allow the mRNA to be recognized by the protein synthesis machinery and protect it from degradation

characteristic of polymerase 3

They can work in only one direction. DNA Poly can add deoxyribonucleotides only to the 3' end of a growing DNA chain. As a result, DNA synthesis always proceeds in the 5' > 3' direction.

topoisomerase

This enzyme cuts DNA, allows it to unwind, and rejoins it ahead of the advancing replication fork.

lagging strand synthesis

This means that DNA polymerase can't just add nucleotides to the strand. Your body handles this by adding RNA primers (DNA primase) at the openings. And then once you have the RNA primer, polymerase can start adding nucleotides in the 5 prime to 3 prime direction. Your body does this process in fragments, called Okazaki fragments. This is a slower process than leading strand synthesis. Hence, "lagging" strand. After your body has a bunch of these fragments, they are put together by an enzyme called DNA-ligase. Not only will the strands be put together but then you also have the RNA being actually replaced with DNA and then when It's all said and done, you are going to have a strand of DNA being replicated. So now you have 2 double strands of DNA.

the stop codon is ___

UGA, UAA, UAG

lagging end replication problem

Unlike bacterial chromosomes, the chromosomes of eukaryotes are linear (rod-shaped), meaning that they have ends. These ends pose a problem for DNA-replication. The DNA at the very end of the chromosome cannot be fully copied in each round of replication, resulting in a slow, gradual shortening of the chromosome. To prevent the loss of genes as chromosomes ends wear down, the tips of eukaryotic chromosomes have specialized DNA caps called telomeres. Telomeres consist of hundreds or thousands of repeats of the same short DNA sequence, which varies between organisms but is 5'-TTAGGG-3 in humans and other mammals.

conservative

When several codons specify the same amino acid, the first tow bases in those codons are usually identical.

nearly univeral

With a few minor exceptions, all codons specify the same amino acids in all organisms.

what is a mutation?

a change in the normal base sequence of DNA

A mutation that knocked out the proofreading function of DNA polymerase would result in __________.

a higher than normal rate of DNA synthesis errors

a cap is added on 1 end,

a polyA tail extended on the other end

What is responsible for termination of transcription in eukaryotic protein-coding genes?

a polydenalation or poly A signal

decondensed (relaxed) parts of chromatin

active genes

within a cell type genes fall into 3 general categories

always on or expressed, always turned off, expressed in response to environmental cues.

DNA primase

an RNA primer which then allows DNA polymerase to add nucleotides to the correct bases

rRNA

are ribozymes

aminoacyl-tRNA synthetases

attach correct amino acids to tRNA

Single Stranded DNA- binding proteins (SSBPs)

attach to the separated strands of DNA to prevent them from snapping back into a double helix.

each tRNA has a unique synthetase-why?

because each tRNA has only 1 amino acids

chromatin remodeling

between condensed and decondensed forms is a way of gene regulation

regulatory transcription factors

bind to DNA and alter rates of transcription by interacting with RNA polymerase- to increase or decrease transcription. Activated by signals and bind to specific regions

what is the purpose of SSBP's?

bond to nucleotides of DNA and prevent them from hydrogen bonding

What would be the consequence(s) for DNA synthesis if primase were defective?

both leading and lagging synthesis would be incomplete

DNA helicase

breaks the hydrogen bonds between the base pairs in that location and opens the double helix there. This reaction causes the two strands of DNA to separate in the replication fork.

dNTP

building blocks. Has 3 phosphates like ATP

totipotent

can become any cell type

pluripotent

can become multiple cell types

multipotent

can become several cell types

tamoxifen

can bind to the estrogen receptor and block its action in some cells...

what do the cap and the poly A tail do?

cap- how the ribosome recognizes and stabilizes mRNA. poly A tail- gives time to slow down DNAses and RNAses from eating it -long poly A tails are more stabile

gene

carries information to produce or manufacture for a RNA molecule or a protein molecule.

mutation may cause a:

change in DNA --> change in mRNA---> change in amino acid sequence---> may affect protein function

epigenetic changes

change in the structure of DNA without changing base sequence ---> leads to changes in gene expression. ex. histone acetylation, histone methylation, DNA methylation

if you change DNA, it'll ____

change the mRNA

types of cellular signals

chemicals (hormones) light, sound, temperature, vibration

hexa gene

codes for alpha subunit of beta-n acetylhexosaminidase A (chromosome 15)....a lyosomal enzyme that breaks down glycolipids.

A group of three bases that specifies a particular amino acid is called a _____

codon.

cells with lower levels of transcription

condensed heterochromatin (dark)

properties of the genetic code:

conservative, nearly universal, unambiguous, non overlapping, redundant

mRNA

contains info of gene

In eukaryotic cells, translation occurs in the ________.

cytoplasm

codons of mRNA order amino acids in protein. this occurs in the _____

cytoplasm

protein synthesis takes place in the

cytoplasm

patterns of epigenetic modifications can be inherited by

daughter ells during cell division

cystic fibrosis

delta f508 3 nucleotide deletion. thick musus in lungs, pancreas, and intestines.

RISC

destroys mRNA, very specific to mRNA

protein receptor

determines which cells will respond to a particular signal.

cells differ due to

differential gene expression

stem cells can:

differentiate into different cell types: blood, muscle, nerves

undifferentiated

do not look like the type of cell which they arose, not expressing the pattern of genes for the cell type from which it arose, associated with higher malignancy, used to grade ttumors-how differentiated the cells are

receptors are proteins that are

dynamic

the triplet genetic code

each 3 letter word on mRNA is called a codon

________ activate regulatory proteins that alter gene expression

environmental cues/signals

DNA polymerase 3

enzyme that catalyzes the addition of dNTP to the growing strand. can only add to the 3' end direction of replication- 5' to 3'

cells with higher levels of transcription

euchromatin (relaxed and lighter portions of the cell)

patterns of what genes can be turned on/off in certain cell types occurs primarily in development:

fertilized egg (zygote) to mitosis ---> developing embryo ---> organism

tRNA

forms loops and stems. They bring the amino acid at one end. Anticodon at the other end binds to codon on mRNA. Each tRNA can only attach to 1 type of amino acid

how does RNA polymerase know where to copy?

gene: segment of DNA that codes for a protein/RNA

DNA ligase

goes all the way to the end then disassembles

Discuss how researchers "cracked" the genetic code

he first step in "cracking the genetic code was to determine how many bases make up "word". In this genetic language, words are amino acids. In a sequence of mRNA, how long is a message that specifies one amino acid.

HAT

histone acetyl transferae (adds acetyl group)- causes chromatin 2 relax. (both are activated in response to certain signals)

HDAC

histone deacetylase (removes acetyl group) -causes chromatin to recondense by removing histone

promoters

in eukaryotic DNA are more diverse than bacterial promotes. Many eukaryotic promoters include a sequence called the TATA box, centered about 30 base pairs upstream of the transcription start site, and other important sequences that vary more widely .

how do mutations occur?

in the S phase of replication when DNA is being copied prior to cell division

condensed parts of chromatin

inactive genes

protein synthesis happens in 3 steps

initiation elongation termination

the structure and function of ribosomes

large and small subunits are a mixture of rRNAs and proteins. rRNAs catalyze protein synthesis

mutagens

lights or chemicals that are limited to mutations. ex. UV light

Codons are part of the molecular structure of _____.

mRNA

only ____ will produce protein

mRNA

translation

mRNA is read and converted into a protein

a gene codes for a single RNA molecule, could be:

mRNA, tRNA, rRNA, or microRNA

the start codon is ___

met

That is, an amino acid could be specified by

more than one triplet of bases.

eukaryotes

multiple linear strands of DNA. DNA rep. can occur more often (faster)

promoter proximal element

next to promoter

A point mutation that results in an early stop codon within a protein is a ______.

nonsense mutation

most mutations occur during

normal DNA replication. can occur due to exposure of mutagens

chromatin is arranged into ______ like beads on a string

nucleosomes

DNA double helix ---> strands separate ---> only one strand is copied to mRNA. this all occurs in the ______

nucleus

DNA is in the _______

nucleus

poly a signal

o Termination of transcription for eukaryotic protein-coding genes differs substantially form termination in bacteria. In eukaryotes, a DNA sequence called the polyadenylation signal, or Poly(A)signal-(In eukaryotes, a short sequence of nucleotides near the 3' end of pre mRNAs that signals cleavage of the RNA and addition of the poly(A) tail.), neat the end of each gene is transcribed. The RNA downstream of the poly (A) signal sequence is cut by enzyme as the polymerase continues to transcribe the DNA template, and transcription is terminated. To put it another way, in bacteria, transcription ends at a distinct site in each gene; in eukaryotes, transcription ends variable distances form the poly(A) signal.

always on or expressed and always turned off

occurs during fetal development

how many tRNA are there for 61 different codons on the mRNA?

only about 40- that means same tRNA anticodon has to bind to several different codons. how? by woblind at the 3rd position of the codon (wobble hypothesis)

template strand

only one strand of DNA is copied

chromatin must ______ for transcription to occur

open up

A DNA replication bubble forms at a specific sequence of bases called the ___________.

origin of replication

tay-sachs

over 100 different mutations

An aminoacyl-tRNA that enters the A site of the ribosome will next occupy which site?

p site

what is the type of bond that is formed between amino acids during elongation in translation?

peptide bond

A frameshift mutation that occurs very early in a protein sequence would have what effect on the protein's structure?

primary, secondary, and tertiary structure

The enzyme that synthesizes RNA primers for use in DNA replication is _______________.

primase

DNA synthesis

proceeds in only one direction. involves a condensation reaction that forms phosphodiester bond between the 3' carbon on the end of a DNA strand and the 5' carbon on an incoming dNTP monomer.

transcription

process of making mRNA from a gene

any functional gene has a ____ region, a _____ region, and a ____ region

promoter, transcribed, terminator

cadherin

proteins link cells

in prokaryotes, sigma binds to the promoter to initiate transcription in bateria-

recognized -35 and -10 boxes in the bacteria promoter. -all genes in these boxes will be the same

the genetic code can be

redundant

what is a gene?

region of DNA that carries information for a discrete hereditary characteristic, Usually corresponds to:a single protein or a single RNA molecule

introns

regions in the genes that are copied, but removed from mRNA after transcription

enhancers

regulatory sequences far from promoter

DNA polymerase 1

removes RNA on leading and lagging strand to replace with DNA

telomeres

repetitive regions at the end of chromosomes. they act as caps that protect the internal regions of the chromosomes, and they're worn down a small amount in each round of DNA replication.

_____ are the site of protein synthesis

ribosomes

chromatin must be relaxed for RNA polymerase to bind to promoter

roles of HAT and HDAC

what is the genetic code?

rules that govern the relationship between the DNA or RNA and sequence of amino acids in a protein

The Meselson-Stahl experiment supported which mechanism for DNA replication?

semi conservative

replication is _____

semi-conservative

alternative splicing

several proteins can be manufactured from a single gene

start codon

signals that protein synthesis should begin at that point on the mRNA molecule. This codon specifies the amino acid methionine, it sets the reading frame of the message, showing which set of three-base triplets constitute "words".

prokaryotes

single large circle of DNA-contains essential genetic info

what is the purpose of the 5' guanine methylated cap?

small ribosomal subunit will bind to this region in translation

plasmids

smaller rings of DNA, contain helpful info (i.e. antibiotic resistance)

introns are removed from mRNA by

splicing- introns are removed exons are spliced together

lagging strand replication process

steps 1-4 are the same as in the leading strand process. 5. DNA polymerase 3 builds first okasaki fragments. 6. DNA polymerase 3 synthesizes 2nd okasaki fragments 7. DNA polymerase 1 replaces DNA primer with DNA nucleotide in a 5' to 3' direction. 8. DNA ligase closese gap between DNA fragments.

lagging strand

synthesized away from replication fork. -synthesized in fragments, Okasaki fragments, that will later be joined. 3' to 5'

leading strand

synthesized toward replication fork. 5' to 3'

_____ bring amino acids to ribosomes

tRNA

There are three stop codons, also called ______

termination codons (UAA,UAG, and UGA).

DNA polymerase can only add nucleotides on

the 3 prime end

when the poly A tail gets critically short,

the cell will get rid of the mRNA

What provides the energy for the polymerization reactions in DNA synthesis?

the deoxyribonucleotide triphosphate substrates

What is a telomere?

the ends of linear chromosomes

RNA polymerase

the enzyme that copies DNA into RNA

polymerase 3

the enzyme that is primarily responsible for copying E. Coli's chromosomes before cell division.

Which strand of DNA is synthesized toward the middle of the replication bubble?

the lagging strand

most receptors are found in

the plasma membrane

RNA polymerase must bind to

the promoter

for lipid soluble signals,

the response is direct

In eukaryotes, the size of the primary transcript is generally ________ the gene in the template DNA strand.

the same length as

DNA polymerase

this protein catalyzes DNA synthesis

how do cells change chromain structure?

through activity of enzyme that adds on an acetyl group to a protein

in P site,

translation has been initiated

what happens to eukaryotic mRNA after transcription?

translation- eukaryotic mRNA gets processed before coming out of the nucleus

the triple genetic code is:

unambiguous, universal, and conservative

gene expression

what genes are being actively transcribed

what happens to prokaryotic mRNA after transcription?

while transcription is still in progress, prokaryotic mRNA begins translation of proteins

conservative replication

would leave the two original template DNA strands together in a double helix and would produce a copy composed of two new strands containing all of the new DNA base pairs.

semi conservative replication

would produce two copies that each contained one of the original strands and one new strand.

During transcription, in which direction is (1) RNA synthesized and in which direction is (2) the DNA template "read"?

(1) 5'—>3' (2) 3'—>5'

There are only four different bases in ribonucletiods

(A,U,G, and C), so a one-base code could specify only four different amino acids.

Outline the central dogma of molecular biology

* DNA--->(transcription)RNA---->(translation)PROTEIN

RNA polymerase binds to the promoter with the help of several other proteins-

-1 protein opens the DNA double helix -RNA polymerase opies the transcribed region -terminator stops the copying process

redundant

-More than one codon for one amino acid -61 codons for 20 amino acids -All amino acids except methionine and tryptophan are coded for by more than one codon. This is sometimes referred to as degeneracy of the code.