Genetics

Front 1

Mendelian genetics: First Law: four principles of inheritance

Back 1

- genes exist in alternate form

- two alleles for each trait, one from each parent

- two alleles segregate during mitosis = gametes

- dominant or recessive concept. homo vs hetero

Front 2

Mendelian genetics: Testcross

what is needed?

Back 2

- cross with phenotypically recessive organism

-

Front 3

Non-Mendelian Inheritance Patterns

Incomplete Dominance

Codominance

Back 3

- an allele is incompletely dominant if the phenotype of the heterozygote is an intermediate of the homozygotes.

- when multiple alleles exist for a gene and more than one is dominant.
> ex. BLOOD TYPE

Front 4

Genetic Problems

- Nondisjunction
> gamete sequences for nondisj. in meiosis 1?

- Chromosomal breakage

Mutations

Back 4

- failure of homo. chromosomes to separate during meiosis 1 or sister chromatids to separate in meiosis 2.
> (n+1) (n+1) (n-1) (n-1)
> (n+1) (n-1) (n) (n)

- may occur spontaneously or be induced by environ.

- gets its on flashcard, too much info.

Front 5

Genetic Problems: Mutations

Mutagenic Agents

Mutation Types

Examples of Genetic Disorders

Back 5

- induces mutations. generally carcinogenic

- nitrogen bases can be ADDED, DELETED, or SUBSTITUTED.
> changes can alter expression.
> genetic code is degenerate because not always will a change in sequence change expression.

- Phenylketonuria (PKU) - molecular disease caused by inability to produce proper enzyme to digest phenylalanine. causes physiological problems.

- Sickle Cell Anemia - disease in which red blood cells become crescent shaped (due to defective hemoglobin). carries less oxygen.

Front 6

Molecular Genetics: DNA

Structure - general
> base types?
> what happens when more C/G?

Back 6

- ability to self-replicate

- basic unit is nucleotide; deoxyribose (sugar) bonded to a phosphate and nitrogenous base.
> Pyrimidines: Cytosine, Uracil, Thymine
> purines: Adenine and Guanine.
- sugar phosphate chains on outside of helix, bases on inside.
- when more C/G pairs = higher melting point

Front 7

Molecular Genetics: DNA

Function
> DNA replication

Back 7

- Helicase unwinds helix
- RNA primer starts replication at 5' end..
- DNA polymerase goes on both strands

Front 8

Molecular Genetics: RNA

Structure

types?

Back 8

- not deoxyribose sugar, its ribose sugar.

- uracil instead of Thymine, single stranded.

- mRNA, rRNA, tRNA

Front 9

Molecular Genetics: types

mRNA

rRNA

tRNA

Back 9

- complement of DNA, travels from nucleus to ribosomes.
> monocistronic (codes for 1 polypeptide) eukaryotes
> polycistronic (codes for many) in prokaryotes

- structural component of ribosomes, most abundant of all RNA types. rRNA is synthesized in the nucleolus

- small RNA, found in cytoplasm. aids in translation of mRNA. brings amino acids to ribosome during translation. 1 tRNA for each amino acid.

Front 10

Molecular Genetics: Protein Synthesis

Transcription
> initiation
> elongation
> termination

Back 10

INITIATION: RNA polymerase recognizes TATA box promoter sequence.

ELONGATION: RNA polymerase adds on in 5'->3'. uses transcription factors to help,

TERMINATION: when RNA polymerase recognizes end sequence of the new transcript.
> prokaryotes = finished product
> eukaryotes = introns get spliced out, 5' head and poly-A tail add to exons. read to move into cytoplasm.

Front 11

Molecular Genetics: Protein Synthesis

Translation
> what does it involve?
> polypeptide synthesis?
> initiation
> elongation
> termination

Back 11

- tRNA, Ribosomes, mRNA, amino acids, enzymes
> Ribosomes: two subunits, three binding sites (APE)
> P site binds to tRNA attached to growing polypeptide chain, while A site binds to incoming aminoacyl-tRNA complex.

- ribosome scans bound mRNA and binds AUG (initiation codon).
- hydrogen bonds form between mRNA codon in the A site and its complement, peptide bond formed between amino acid attached to tRNA in A and amino acid attached to tRNA in P site. translocation occurs, when amino acid-less tRNA in P site is moved to E site and expelled, peptidyl-tRNA from A site moves to P site
- when one of the stop codons is read (UAA, UGA, UAG)
> once polypeptide is released, immediate conforms to protein shape.

Front 12

Molecular Genetics: Cytoplasmic Inheritance

where else is DNA found outside of nucleus>

Back 12

- mitochondria, chloroplasts, cytoplasmic bodies.
> drug-resistance often is regulated by plasmids.

Front 13

Molecular Genetics: Bacterial Genetics

Bacterial genome
what is sometimes present? whats an Episome?

Back 13

- single circular chromosome located in nucleoid region.
> sometimes there are plasmids.
> Episomes: plasmids that are capable of integration into bacterial genome.

Front 14

Molecular Genetics: Bacterial Genetics

Replication

Back 14

- begins at ORI, proceeds in both directions simultaneously.

Front 15

Molecular Genetics: Bacterial Genetics

Genetic Variance
> transformation
> conjugation
> transduction

Back 15

- reproduce by binary fission and proliferate rapidly.
> asexual process, so how is there genetic variance?
> Transformation: foreign plasmid integrates into bacterial chromosome through recomb.
> Conjugation: can only be done by bacteria with sex factor plasmids. SEX between bacteria.
> Transduction: spread style, viral progeny. bacteriophage attaches to bacterial membrane, secretes genome inside, mixes with bacterial chromosome.

Front 16

Molecular Genetics: Bacterial Genetics

Gene Regulation
>operon? genes (4)?

inducible vs. repressible systems

Back 16

- operon directs regulation
> structural gene - codes for proteins.
> promoter gene - initial binding site for RNA polymer.
> operator gene - represses binding site
> regulator gene - codes for synthesis of repressor molecule.
> repressor binds to operator, block transcription of structural gene.

Front 17

Molecular Genetics: Bacterial Genetics

Gene Regulation

inducible vs. repressible system

Back 17

- require presence of inducer for transcription to occur.
> repressor binds to operator. needs inducer to bind to repressor, this complex releases, enabling transcription.
> enzymes are an example of inducible system.

- constant state of transcription, unless corepressor is present to inhibit transcription.
> repressor inactive until it combines with corepressor.

Front 18

Molecular Genetics: Bacteriophage

definition? two cycles?

Back 18

- is bacteria specific viruses
> Lytic Cycle

> Lysogenic Cycle

Front 19

Bacteriophage: Lytic Cycle

what happens?
what are bacteriophages in this cycle called?

Back 19

- phage DNA takes control of bacteria's genetic machinery, makes tons of progeny.
> bacterial cell then bursts (lyses), releasing new virions, increasing infection

- bacteriophages in this cycle are called VIRULENT

Front 20

Bacteriophage: Lysogenic Cycle

what happens?

Back 20

- if bacteriophage doesn't lyse its host cell, it becomes integrated into host genome as prophage form (harmless).
> when environmental or spontaneous activation happens, prophage re-emerges and enters lytic cycle.

Front 21

Molecular Genetics: Genetic Technology

Gel electrophoresis

Blotting
> Southern
> Western
> Northern

DNA Amplification

Back 21

- used to seperate molecules based on their size using charge gradient.

- Blotting
> Southern: allows for detection of specific DNA sequence in a sample of DNA.
> Northern: detection of RNA
> Western: used for detection of specific proteins

- Amplification:
> performing PCR
> DNA cloning.

Front 22

Molecular Genetics: Genetic Technology

DNA sequencing
> chain termination method

Restriction Fragment Length Polymorphisms (RFLP)

Back 22

- use chain termination method. uses ddNTP (they prevent addition of more nucleotides in replication reaction), then seperate out single strand DNA using electrophoresis.

- used to check for presence of disease. restriction enzymes bind to and cut double stranded DNA at certain sequences. enables to see variations in fragment length, which leads to a different sequence.
> pattern checking.