Nucleic acids Flashcards
What does adenine bond with?
thymine
What does guanine bond with?
cytosine
What causes the complimentary base pairings?
size of the nucleotides
hydrogen bonding between bases
What does the number of purines equal?
number of pyrimidines
What are purines?
adenine
guanine
How many rings so purines have?
double ringed
What are pyrimidines?
thymine
cytosine
How many rings do pyrimidines have?
single ring
When does the replication of DNA occur?
S phase of cell cycle interphase
How does DNA replicate?
-The enzyme helicase unzips the DNA (breaks hydrogen bonds)
-SSB (single stranded binging) proteins bind to DNA strands
- DNA polymerase (an enzyme) makes new DNA from deoxyribonucleotides
-Primase makes the primer that tells polymerase where to work
Ligase repairs any breaks in the sugar phosphate backbone
What direction can DNA polymerase work?
5’ (prime) to 3’ (prime)
What is the strand that goes in the 5’ to 3’ direction called?
Leading strand
What is the strand that goes from 3’ to 5’ called?
lagging strand
Why is the lagging strand slow?
Because polymers has to put down more primers
What are Okazaki fragments?
Fragments of synthesized DNA on lagging strand
What are primers made of?
RNA
Why is DNA replication known as semi-conservetive?
Because each new DNA contains one old strand and one new one
What is a gene?
The segment of DNA that specifies a specific amino acid sequence
How is a gene stored?
in the form of a nucleotide acid
What does a difference in base sequence cause?
A difference in protein structure
How do genes control protein synthesis?
Not directly
first pass genetic information to RNA
How many types of RNA are involved in protein synthesis?
3
What are RNA’s 4 possible nitrogen bases?
adenine
guanine
cytosine
uracil
What does adenine pair with in RNA
uracil
What is RNA composed of?
phosphate
sugar-ribose
nitogen base
What are the 3 major classes of RNA
mRNA
rRNA
tRNA
What does mRNA do?
carries genetic information from DNA to ribosomes
What does rRNA do?
Site of protein assembly
What composed ribosomes?
rRna
What happens in transcription?
RNA polymerase connects complimentary RNA bases to the DNA to form mRNA
What are the two steps of protein synthesis?
Transcription
Translation
Where does transcription takes place?
Nucleus (because that’s where DNA is)
What happens to mRNA after it is formed?
Leaves the nucleus
goes through the cytoplasms where it attaches to a ribosome
What do tRNAs hold
amino acids
What is the monomer for a protein?
amino acids
What controls what tRNAs (and therefore what amino acids are transferred) come to the ribosome
mRNA
What are tRNA’s looking for
complimentary bases on mRNA
What happened when tRNA find a complimentary base pairing on the mRNA
It transfers the amino acids`
What is a codon
A sequence of 3 nucleotides which form a unit of genetic code
What contains an anti-codon?
tRNA
What are the steps of translation?
Chain initiation
chain elongation
chain termination
What are the causes of gene mutation?
errors in replication
mutagens
transposons
What are mutagens?
environmental influences
What are transposons?
genes that move to a new location and disrupt sequences
What is DNA’s function in the cell
control cell activities
What is RNA’s function in the cell?
Facilitates protein synthesis
What is recombinant DNA (rDNA)?
When DNA from more than one source is isolated and recombined
