Test 2 Flashcards
How are covalent bonds formed in DNA synthesis?
By sharing electrons and using energy to power bond formation
What is the universal name for the energy molecules needed in DNA synthesis?
dNTP, or deoxynucleotide triphosphate
Which direction does DNA form?
from the open 3’ end of the new strand (therefore, from 5’ to 3’)
What is needed to synthesize DNA?
-dNTPs
-a Template strand
-DNA polymerase
-primers (aka a free 3’ end)
What are the steps of DNA synthesis?
Denaturation, where heat is used to separate DNA strands
Annealing, where primers are added for the 3’ end
Extension, where replicative polymerase adds dNTPs to the template strand
What is the relationship between DNA and primers?
DNA gets replicated from wherever the primer is placed
What are primers?
Short DNA or RNA strands with an open 3’ end to be built off of
What are probes?
Complementary primers are designed, usually with a fluorescent addition, to locate complementary section of the parent strand
What are the two notable DNA Polymerase types?
Replicative polymerase is an enzyme that binds to the RNA primer and pulls in dNTPs to build the complementary DNA strand
Polymerase 1 removes the RNA primers and replaces them with DNA on the lagging strands
What is Helicase?
An enzyme that unzips the DNA double helix
What is Primase?
An enzyme that builds and places RNA primers on the parent DNA strand
What is an SSBP?
Proteins that hold open separated strands once helicase separates them
What is Ligase?
An enzyme that creates bonds to fill nicks in the sugar phosphate backbone caused by Okazaki fragments
What is Topoisomerase?
Creates nicks in the sugar phosphate backbone that allow the double helix to unwind without creating tension, and then quickly fills those gaps
What are okazaki fragments?
Short segments of replicated DNA on the lagging strand between primers.
What is a mutation?
A mistake in DNA replication that is not caught and fixed by one of many processes, and is then replicated and made permanent
What are germ cells?
Haploid egg and sperm cells
What is a homolog?
Two corresponding but not identical chromosomes
Describe the process of Meiosis
Prophase I - Crossover occurs at the Chiasma
Metaphase I - Homologs line up in the middle
Anaphase, telophase, and cytokinesis all proceed as in Mitosis
Prophase II - DNA condenses (same as in mitosis)
Metaphase II- Chromosomes align as usual
Anaphase II- Homologs are separated
Telophase and cytokinesis- two haploid daughter cells are yeilded
How should you write out the number of genotype combinations in an exam?
Number of letter options ^number of total options
(ex: with Aa Bb Cc, answer is 2^3)
Define Allele
Different versions of the same trait
What is dominance and why does it occur?
Dominance is where the gene presents in a heterozygote, and it occurs because the signal it codes for still proceeds and is not hindered, even if only one allele is present
How do you calculate probability of offspring?
By multiplying the fractions, if they are independent, or by adding them if they’re ordered.
What is incomplete dominance?
Where there is more than one dominant trait, and the traits present as “less” than what a fully dominant trait would.
What is codominance?
When there is more than one dominant trait and the traits present equally as dominant
