Chapter 12 Flashcards
What complex regulates the cell cycle? What is the cyclical molecule?
cyclin-CDK complex regulates the cell cycle, it is not active unless it is bound to cyclin, but it is always present in the cell
How many checkpoints are there? Between what stages in the cell cycle are they found?
G1 checkpoint (DNA damage)
G2 checkpoint (growth factor)
Spindle Assembly checkpoint (spindles are attached for chromosomes)
A patient has cancer. It is targeted that he has a mutation in the p53 gene. Why would a mutation in this gene cause cancer?
DNA damages activate and phosphorylate p53, inhibiting the cell cycle, p53 is a tumor suppressor so when p53 is mutated cell growth continues.
What are the two genes that regulate the cell cycle?
Proto-oncogenes: drive the cell cycle
Tumor suppressor cells: inhibit the cell cycle
Ras is an example of _________
proto-oncogene
Metastasis definition
cancer cells that migrate through the bloodstream and spread to other parts of the body
What is the multiple-mutation model?
It shows how multiple mutations can accumulate and cause metastatic cancer.
There are two ways in which cell death can occur. Name and describe them.
Apoptosis - programmed cell death
Necrosis - occurs when a cell is damaged or starved for oxygen or nutrients
Why do restriction enzymes exist?
Restriction enzymes exist to protect bacterial cells from phages. Bacteria that carry restriction enzymes methylate their DNA at sites that correspond to the restriction enzyme recognition site.
What are restriction enzymes?
an enzyme produced by bacteria, cleave DNA molecules at or near a specific sequence of bases.
The enzyme that catalyzes the addition of new nucleotides to a growing DNA strand is:
DNA polymerase
As a piece of linear DNA is replicated, the leading strand will have _____ RNA primer(s) and the lagging strand will have _____ RNA primer(s).
one, many
Telomerase is fully active in _____ and _____ cells, but almost completely inactive in _____ cells.
germ, stem, somatic
The polymerase chain reaction (PCR) is used to generate:
multiple copies of a targeted region of DNA
Each end of a eukaryotic chromosome is capped by a repeating DNA sequence called the telomere.
True
What is the correct order of steps during PCR?
denaturation, annealing, extension
In a long DNA molecule, each origin of replication produces a _____ with a _____ on each side
replication bubble, replication fork
The enzyme responsible for joining Okazaki fragments together during DNA replication is:
DNA ligase
What would occur after one generation if DNA replication were conservative
equal amounts of heavy and light DNA
What would occur after one generation if DNA replication was dispersive?
DNA of intermediate intensity
What would occur after two generations if DNA replication were dispersive?
DNA of intermediate intensity
What are the two basic steps of DNA replication?
Double helix unwind
Nucleotides Added
What is the main difference between the leading and lagging strands?
The lagging strand has multiple primers and replicate in fragments
What replaces the primers with DNA?
DNA polymerase
What happens if one of the pairs is incorrectly matched?
DNA polymerase proofreads and fixes it (Exonucleus Activity)
Helicase
Use energy from ATP hydrolysis to unwind the DNA, creating replication fork
Ligase
replaces primers with DNA, DNA repair, phosphodiester linkage
Primase
synthesizes primer, adds RNA primer
DNA polymerase
Adds a nucleotide to a growing strand, proofread, removes primers
Topoisomerase
Relieves stress
Telomerase
Adds telomere sequences to the ends of chromosomes, prevent strands from shortening
Single-Stranded Binding Proteins
keeps the strands from getting back together
Where does replication start
Ori
What 4 things does the PCR technique require?
DNA template, nucleotide, polymerase TAQ, 2 primers
PCR results in many copies of the DNA. What is this called?
Amplification
What are the three steps in PCR?
Denaturation, Annealing, Elongation
Who showed that semiconservative replication was the correct model
Meselson and Stahl
What was DNA labeled within the Meselson and Stahl experiment?
15N and 14N (15N made the DNA denser)
DNA polymerase needs a _____ in order to latch on to the strand
primer
The primer is ______________ to the DNA template
complementary
DNA polymerase adds nucleotides to the ___ end of the primer
3’
Synthesis of the lagging strand occurs in small, discontinuous stretches called what?
Okazaki fragments
The final phosphodiester linkage between fragments is catalyzed by ________________
DNA ligase
What kind of bond does DNA ligase add to join fragments
covalent
__________________________ proteins bind to the ori DNA to start replication
Replication Complex
Eukaryote chromosomes have repetitive sequences at the ends called
telomeres (they prolong cell division)
Copies of DNA sequences can be made by ______ technique
PCR
PCR: DNA template fragments are denatured into single strands by ______. Primers ______ to the DNA strands. New DNA strands are synthesized by DNA polymerase using ______.
Heating, anneal, dNTPs
Complementary DNA primers are 18-20 bp:
made in the lab using fragment DNA sequence information
Does TAQ denature at high temps
no
Gel electrophoresis provides information on what 3 things
number of different sized fragments, sizes of DNA fragments, concentration of DNA
Bacteria use __________________ to cleave virus DNA at specific sequences into smaller noninfectious fragments
restriction enzymes
To protect bacteria cell DNA: __________ add methyl groups to restriction sites on the cell’s own DNA
methylases
The restriction enzymes passes over the ___________ sequence on bacterial DNA but cuts the ____________ viral DNA
methylated, unmethylated
____________ groups protect DNA
methyl
Restriction Enzymes _____ DNA at specific DNA sequences
cleave
Resitrction sites are usually what?
palindromic (same backward or forward)
Splicing to make recombinant DNA: Overhangs are known as ________
sticky ends
Southern Blotting
Technique used to detect specific DNA sequences in DNA sequencing
What are dideoxynucleotides?
Dideoxynucleotides are chain-elongating inhibitors of DNA polymerase, used in the Sanger method for DNA sequencing
When you mix dideoxynucleotides and deoxynucleotides what happens
you will get a random mix of every length because ddNTPs stop the chain
How are the different lengths of the Sanger Method distinguished?
By the different color codings on the DNA strands
How are the Sanger Method pieces arranged
shortest to longest
The whole genome shotgun sequencing needs what?
A computer to find the overlaps and pair them up
What way do you read DNA? What way do you synthesize DNA?
Read 3’ to 5’
Synthesize 5’ to 3’
Sticky ends are used for
recombinant DNA
