DNA structure and replication
messenger RNA formation occurs in the ________ (cell structure). the name of this process is _____?
nucleus transcription
anticodon
the 3 nucleotides on the tRNA
genetic code
the sequence of nitrogen bases directs the sequence of amino acids in a protein
base sequence
genetic code
where does translation take place
ribosome
codon
set of 3 nucleotides of mRNA -each codon is a code for a specific amino acid, or to start/stop translation
amino acids are transported to the ribosomes by
tRNA
how many codons combinations are possible?
there are 20 amino acids there are 4 bases codons are the bases in groups of 3 (triplets) 4 to the third power= 64 possible codons
fixing errors
-DNA polymerase makes an error about every 1 million base pairs 1. the mistake is often recognized and removed by DNA polymerase during proofreading... which then corrects sequence 2. after proofreading estimated mutation rate decreased to every 1 billion base pairs
mRNA
(messenger RNA) -carries gene's instructions from nucleus to ribosomes
rRNA
(ribosomal RNA) -part of ribosome that helps translate mRNA to make protein
differences between DNA and RNA
*DNA:* -double helix -larger -a, *T*, G, C -deoxyribose -found in nucleus only -thousands of genes *RNA:* -single helix -smaller -A, *U*, G, C ribose -in nucleus and cytoplasm -copy of one gene
compare the similarities and differences between RNA synthesis and translation
*translation:* -aas -tRNA -ribosome -in cytoplasm -makes a polypeptide chain *trascription/RNA synthesis:* -RNA created -in nucleus *both:* -nitrogen bases are involved
DNA segments
-double strand of nucleotides -base pair rule --> purine bonds with pyrimadine A bonds with T C bonds with G -untwisted "ladder" --> the side poles on the "ladder is the deoxyribose and the phosphate and the cross rings are the nitrogen bases -complimentary pairs
DNA structure
-nucleotides ([monomers] building blocks of DNA) are made up of 3 parts a. 5 carbon sugar called deoxyribose b. phosphate group c. nitrogen base -the nucleotides of DNA differ by bases
what is the complementary RNA strand for this strand TAC GGG GGC GTA ACC ACA ACT
AUG CCC CCG CAU UGG UGU UGA
what is the complementary RNA strand for this strand TAC CTG TTA AGC TAC AAA ATT
AUG GAC AAU UCG AUG UUU UAA
what is the complementary RNA strand for this strand TAC CGG ATG CCA GAT CAA ATC
AUG GCC UAC GGU CUA GUU UAG
what is on the 5' side
a phosphate F sound
messenger RNA leave the nucleus through
a pore in the nuclear envelope
who discovered that the number of adenines equals the number of thymines
Chargoff
explain why translation must always occur either before or after transcription
transcription must occur first because it makes the code for the bases of mRNA. mRNA is used in translation to create a polypeptide chain through tRNA. without mRNA, translation could not take place, therefore transcription must take place first.
tRNA
transfer RNA transfers amino acids to the ribosome
the DNA molecule has ______ strands
two
what type of bonds hold the nitrogen bases together and the nitrogen base to the deoxyribose
hydrogen bonds also covalent
where is DNA located/created
in the nucleus
what is on the 3' end
just the deoxyribose (no phosphate)
translation
mRNA is decoded to make protein
purpose of DNA replication
needed for growth of the new cell when the cell divides
if some amino acids are not present in the cell when protein synthesis is occurring, will the protein be completed?
no
what is the difference between each of the new DNA strands?
no difference! they are identical
the subunits that make up nucleic acids are
nucleotides
what are the two types of nitrogenous bases found in nucleic acids
purines and pyrimadines
the process of DNA copying itself is ______ and occurs during ___________ of _________ in the cell cycle
replication synthesis interphase
another name for DNA replication and the meaning of the name
semi-conservative replication --> each new DNA molecule is one old strand and one new strand
what is a benefit of DNA taking the shape of a double helix?
since it is wrapped around a histone, it can fit as much genetic material as possible
which RNA preforms each of the following functions: a. transports amino acids to assembly site b. contains blueprint for protein synthesis c. site for protein assembly
tRNA mRNA rRNA
because the strands are complimentary...
they each serve as a template to build a complete DNA molecule
how do genes direct the making of a protein
through an intermediate molecule called *ribonucleic acid (RNA)*
pyrimadines
thymine, cytosine
does the sequence of bases in mRNA determine the sequence of amino acids in a protein. if one base is different (because of DNA mutation), could this change the corresponding amino acid?
yes
what is the complementary DNA strand for this strand TAC GGG GGC GTA ACC ACA ACT
ATG CCC CCG CAT TGG TGT TGA
what is the complementary DNA strand for this strand TAC CTG TTA AGC TAC AAA ATT
ATG GAC AAT TCG ATG TTT TAA
what is the complementary DNA strand for this strand TAC CGG ATG CCA GAT CAA ATC
ATG GCC TAC GGT CTA GTT TAG
starting codon
AUG
steps of DNA replication
1. DNA is unwound and hydrogen bonds are broken to separate the strands facilitated by *helicase* 2. enzymes (*DNA polymerase*) adds complementary base pairs to the 3' end of each of the original strands 3. DNA *polymerase* finishes and "proof reads" the new double helices 4. DNA *ligase* fills in any gaps to create a continuous DNA strand
what does DNA do
1. carries genetic info from one generation to another 2. determine traits of an organism (all proteins produced by cell) 3. be easily copied *found in nucleus of eukarotic cells
how many hydrogen bonds are between adenine and thymine
2
how many hydrogen bonds are between guanine and cytosine
3
how many mRNA bases code for one amino acid
3
discontinuous fragments (*Okazaki fragments*) are linked together on the ____ to the ___ strand (lagging)
3' 5'
new DNA strands are synthesized at the ______ end only, with enzyme activity in the ____ to ____ direction (leading)
3' 5' 3'
lagging strand
3'--> 5' (Okazaki fragments)
for a protein containing 100 amino acids, what is the minimum number of mRNA bases needed
300
leading stand
5'--> 3' (polymerase works well with this)
explain why DNA is said to be *semi-conservative*
DNA replication is said to be semi-conservative because each of the new DNA strands has half of the original DNA molecule
stopping/ending codons
UAA UAG UGA
steps in translation
a. mRNA moves from the nucleus to a ribosome in the cytoplasm b. a specific complementary tRNA binds each codon c. each tRNA carries a specific amino acid; mRNA codons correlates with its amino acid to create a specific polypeptide d. amino acids from incoming tRNAs are linked together sequentially to form a growing protein e. once a stop codon is reached, the protein is finished correlates with
purines
adenine, guanine
does translation occur before or after transcription
after
the mRNA codon is complementary to the ------- on tRNA
anticodon
significance of DNA replication
codes that the cell will do the same job as the original
how does transfer RNA correctly read (translate) messenger RNA
complimentary base pairing
messenger RNA is read at the ________ (cell structure). the name of this process is _________.
cytoplasm translation
what does DNA stand for
deoxyribonucleic acid
what is the shape of the DNA molecule?
double helix -twisted ladder
when does DNA replication occur
during the S phase in interphase
where are the other nucleotides that attach to the new strands on DNA
floating in the cytoplasm
who discovered the shape of the DNA molecule
francis crick and james watson (used information discovered by Rosalind Franklin to create their model)
what catalyzes the reaction of DNA replication
helicase
enzymes names and jobs
helicase -helps strands separate and breaks hydrogen bonds DNA Polymerase -adds complimentary base pairs to the 3' end of each of the original strands -finishes and "proof reads" the newly created DNA strands ligase -fills in any gaps to create a continuous DNA strand
