(4) Chapter 16 Flashcards
What are the two types of nucleic acids?
Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA).
What does DNA provide directions for?
DNA provides directions for its own replication.
How does DNA control protein synthesis?
DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis.
Where does protein synthesis occur?
Protein synthesis occurs on ribosomes.
What is the lagging strand?
The lagging strand is the other new strand that DNA polymerase synthesizes away from the replication fork.
What are Okazaki fragments?
Okazaki fragments are segments synthesized by DNA polymerase III on the lagging strand.
What must happen to RNA primers during DNA replication?
RNA primers must be replaced with DNA.
What is the role of DNA polymerase I?
DNA polymerase I can remove RNA nucleotides and fill in the gap with DNA nucleotides.
What does DNA ligase do?
DNA ligase can join the 5’ end of one DNA molecule with the 3’ end of another.
What type of genome do bacteria have?
Bacteria have a circular genome with a single DNA molecule and 1 origin of replication.
What type of genome do humans have?
Humans have a linear genome with multiple linear chromosomes and multiple origins of replication on each chromosome.
What are telomeres?
Telomeres are special repetitive, non-coding nucleotide sequences at the ends of eukaryotic chromosomal DNA molecules.
What is the function of telomeres?
Telomeres postpone the erosion of genes near the ends of DNA molecules.
How does telomere shortening relate to aging?
Telomeres in somatic cells are generally shorter in older individuals.
What is the role of telomerase in germ cells?
Telomerase is expressed in germ cells to maintain telomeres at their original length.
How might telomeric shortening be protective against cancer?
Telomeric shortening may limit continuous cell division, which can be protective against cancer.
What is the error rate of DNA polymerase?
About once every 100,000 nucleotides, DNA polymerase will mistakenly add the wrong nucleotide.
What exonuclease activity do DNA Pol I and DNA Pol III have?
Both have 3’ to 5’ exonuclease activity to remove mistaken nucleotides.
What is the rate of nucleotide incorporation for human polymerase?
The rate is 50 nucleotides/sec for human polymerase.
What is the rate of nucleotide incorporation for bacterial polymerase?
The rate is 500 nucleotides/sec for bacterial polymerase.
What is the function of helicase?
Helicase unwinds DNA to create two single strands.
What does Single Strand Binding Protein (SSB) do?
SSB binds to and stabilizes the single stranded DNA.
What is the role of primase?
Primase provides an RNA primer to start new DNA strand synthesis.
What does topoisomerase do?
Topoisomerase travels ahead of helicase, ‘nicking’ and swiveling the DNA to relieve torsional strain.
What does Polymerase III do?
Polymerase III assembles new DNA strand in the 5’ - 3’ direction.
What does Polymerase I do?
Polymerase I can remove RNA nucleotides as it adds new DNA in a 5’ – 3’ direction.
What is the function of ligase?
Ligase joins two DNA strands together at their ends.
What is the role of telomerase?
Telomerase maintains telomere length in germline cells to protect the health of gametes.
