D1 - DNA replication Flashcards
What is DNA replication?
The production of new strands of DNA with base sequences identical to existing strands
What is DNA replication required for?
Reproduction, growth, and tissue replacement
What happens during DNA replication?
2 strands must separate
Both original strands are used as templates to build new strands
New strands are formed by adding nucleotides 1 by 1
When finished there are 2 DNA strands
What do both strands of DNA contain?
Both strands of DNA contain an original strand and a complementary strand . This makes DNA replication semi-conservative.
What is helicase?
A ring shaped protein that unwinds and separates the 2 strands of DNA. It breaks apart the hydrogen bonds between bases and allows one strand to be pulled through the ring while allowing the other to pass through.
What are primers?
Short pieces of single-stranded DNA around 20 nucleotides in length. They are given sequences that will make them bind to opposite strands of the template DNA, just at the edges of the region to be copied.
What are Taq polymerases?
An enzyme used in PCR to amplify specific DNA samples
Can withstand high temperatures required for PCR (optimum temp 75-80℃)
Can replicate 1000 base pair strand of DNA in less than 10 seconds at 72℃)
How is temperature used in polymerase chain reactions?
Used to melt, anneal, and elongate DNA. Hydrogen bonds break at melting, annealing lets primers bind, and elongation provides optimum temperature for Taq DNA polymerase which binds to DNA adjacent to the primer
During translation, what is done with mRNA?
The base sequence of mRNA is translated into the amino acid sequence of a polypeptide
What are the 3 components to synthesize polypeptides in translation?
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomes
What does mRNA contain?
A site for ribosome to bind to and a sequence of codons (set of 3 nucleotides) that codes for an amino acid
What type of mutation is sickel cell anemia?
A substitution mutation, has GUG in its sixth codon instead of GAG
What are the only causes for gene mutation?
DNA replication (errors in base pairing that did not get corrected) and mutagens (radiation and chemicals)
What are germ cells?
Reproductive cells, so genetic diseases can be passed down. Most of the time this causes a genetic disease
What are somatic cells?
Body cells, so mutation can’t be passed onto offspring
