Genetics M1

What are the 3 components of DNA?

deoxyribose sugar, phosphate group, nitrogenous base

3' = ?

OH

2 multiple choice options

5' = ?

Phosphate

2 multiple choice options

Oxygens Present

DNA = ?

RNA = ?

RNA = 2, DNA = 1

dNTP

Nucleotide Triphosphates, which are reactants used as the sources of A, C, T, and G for a new strand of DNA.

dNTPs combine their 5' ____ with the 3' ____ of another dNTIP to form...

Phosphate; OH; DNA

3 multiple choice options

Polarity in terms of genetcis

Having 2 distinct ends of something (like a leg)

DNA runs in a ___________ fasion

antiparallel

3 multiple choice options

Adenine and Thymine form ___ hydrogen bonds

2

3 multiple choice options

Guanine and Cytosine form ___ hydrogen bonds

3

3 multiple choice options

Purines definition

Nitrogenous bases with 2 rings

Purines example

Adenine and Guanine

Pyrimidines example

Thymine, Cytosine, and Uracil

Pyrimidines definition

Nitrogenous bases with only 1 ring

Major Groove

Larger gap present within DNA

Minor Groove

Smaller gap in DNA

RNA

commonly single-stranded nucleic acid that contains the sugar ribose

RNA secondary structure

circular structure that arises in a single stranded RNA molecule due to complementary base pairing

%A =

%T

%C =

%G

Genetic info is stored within DNA's ________ __________

base pairs

3 multiple choice options

Major and Minor grooves allow ___________ to interact with regions of base pairs

Proteins

Hybridization/Annealing

The process from which single-stranded DNA/RNA bind to one another to form a double stranded structure.

Meselson-Stahl Experiment

Used isotope of nitrogen to change the weight of DNA N15 & N14, demonstrated that the semi-conservative model is the best description of replication.

Semiconservative Replication

Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental DNA strand and one new DNA strand

2 multiple choice options

Conservative Replication

the parental molecule serves as a template for the synthesis of an entirely new molecule

2 multiple choice options

Dispersive Replication

a disproved model of DNA synthesis suggesting more or less random interspersion of parental and new segments in daughter DNA molecules

2 multiple choice options

Initiator proteins

bind to the origin of replication, separate the strands of DNA, and recruit other replication proteins

DNA Helicase

continues "unzipping" the DNA.

Single-Stranded Binding proteins (SSBP)

protects the unzipped DNA until it is replicated

Topoisomerase

Relieves supercoiling in DNA when it is being unwound

DNA grows when a 5' triphosphate of a dNTP reacts with the ______ of another molecule

3' OH

DNA Polymerase III

synthesis new DNA

What does DNA polymerase III need in order to do its job?

1. dNTPs (building blocks of reaction)

2. A DNA template (old strand that determines which dNTP is added)

3. A 3' OH to add new dNTPs onto

What provides the 3' OH for DNA polymerase III to add a dNTP?

primer

What makes DNA primers?

Primase

DNA Polymerase I

removes RNA primers and replaces them with DNA

DNA Ligase

connects the backbones of adjacent strand fragments

AZT drug was approved for _________ therapy

HIV

What does the AZT drug do?

stops further replication by replacing the 3' OH with a N3 group

Leading strand

Strand of DNA built in the same direction as the replication complex is traveling

Lagging strand

strand of DNA build in the opposite direction that the replication complex travels

Each replication bubble has _____ replication forks

2

3 multiple choice options

Prokaryotes replicate _______ from a single Origin of replication

once

3 multiple choice options

Eukaryotic chromosomes replicate _______________

bidirectionally

Bidirectional replication

replication at both ends of a replication bubble

PCR steps

1. Denaturing

2. Annealing/Hybridizing

3. Extension

What happens during the denaturing step of PCR?

Reaction is heated to 95°C and double stranded DNA is seperated into single strands when hydrogen bonds break

What happens during the Annealing/hybridization step of PCR?

Reaction temperature is reduced to around 55°C to allow primer annealing

What happens during the Extension step of PCR?

Temperature is raised to 72°C and Taq synthesizes DNA

Taq Polymerase

A DNA synthesis enzyme that can withstand the high temperatures of PCR

Mutations are a source of...

sequence variation

Substitution =

changing one nucleotide to another

Transition

purine to purine or pyrimidine to pyrimidine mutation

Transversion

Purine to pyrimidine or pyrimidine to purine mutation

Insertion/Deletion

bases added or removed

mutations may cause an organism to be more or less ______

fit

Do mutations occur in response to a stimuli or randomly?

randomly

The fluctuation experiment asked what?

will a trait for resistance emerge before its needed

Spontaneous Mutation

mutations resulting from normal biological and chemical processes in a cell with a low chance of it happening.

Induced Mutation

Result of mutagens which cause mutations that wouldn't otherwise occur.

Tautomerization

when a base flips to another tautomeric state which has different bonding properties.

What causes a sequence to get messed up by tautomers?

When DNA polymerase replicates the strand when the tautomer pairs to the wrong base.

tautomeric shifts (are/are not) mutations

are not

1 multiple choice option

Mutagens

substances that increase the mutation rate above the baseline spontaneous rate

nucleotide mimics

Bases that look like one of the 4 nucleic bases but base pair randomly

Intercalators

molecules that get sandwiched inside the DNA and disrupt replication machinery causing insertions and deletions

Germline Cells

cells whose descendants are gametes

Soma cells

cells that derive from everything else

Germline mutations

occur in germ cells (sperm or ova) and can be passed to one's children at conception

If a person has a mutation in all their cells, it is likely a _________ mutation

germline

Somatic mutations (are/are not) inherited

are not because the mutation wasn't present in the zygote

Mismatch Repair

The cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides.

How does DNA repair machinery tell which strand is the old or new strand?

the old strand has extra chemical tags that are added after it was fully built.

Base excision repair

Repair mechanism that cuts a large portion of the backbone out and then rebuilds it using DNA polymerase.

Nucleotide Excision Repair

A repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide.

Double stranded breaks can be repaired using...

Homologous Recombination or Non-Homologous end joining

Homologous recombination

Uses homologous DNA as a template to repair DNA

Non Homologous End-joining

A fast, error-prone DNA repair process that rejoins broken double strands by trimming and ligating the ends, often causing loss of genetic information.

Haploid number (n)

number of chromosomes in a gamete

Ploidy

how many homologous "sets" of chromosomes a cell has

Diploid number (2n)

number of chromosomes in a diploid cell

Prophase 1 Meiosis

Chromosomes become visible; nuclear envelope breaks down; crossing-over occurs between non sis chromatids

Metaphase 1 Meiosis

Paired homologous chromosomes line up across the center of the cell

Anaphase 1 Meiosis

homologous chromosomes separate and are pulled to opposite ends of the cell

Anaphase 2 Meiosis

sister chromatids separate

Independent Assortment

generates new haploid sets of chromosomes

The info in each haploid gamete from meiosis depends on...

the alignment of the chromosomes during anaphase

Homologous chromosomes are not/are identical

are not

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Euploidy

complete haploid sets of chromosomes are present

Aneuploidy

having one or more extra or missing chromosomes leading to an unbalanced chromosome amount

Trisomy

3 copies of a chromosome

Monosomy

2n-1

Nondisjunction

Failure of homologs or sister chromatids to separate into different cells

Meiosis I nondisjunction

results in a greater amount of empty cells

Meiosis II Nondisjunction

Nondisjunction occurring during the second meiotic division.

True-breeding

term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate

Hybridized

Crossing 2 true breeding organisms to get a sort of "intermediate"

True-breeding lines are...

homozygous for a particular allele