Plant and Animal Genetics Test 1

What is one of biology's unifying principals?

All Organisms use genetic systems that have a number of common features

Genome

Complete set of genetic instructions for any organism

What makes a good genetic model

short generation time
large but manageable number of progeny
adaptability to laboratory environment
ability to be housed and propagated inexpensively

What is needed for inheritance

-Information storage
-Information copying (replication)
-Information retrieval (translation)
-Ability to vary

What is the anchor of DNA and RNA

Pentose sugar

Does DNA use ribose or deoxyribose?

deoxyribose

Does RNA use ribose or deoxyribose?

ribose

What are purines

Adenine and guanine

What are pyrimidines

cytosine, thymine, uracil

What do you call a nitrogen base linked with the pentose

nucleosides

What is the linker of DNA

phosphate group

Which carbon does the phosphate group link

5'

What is a full unit of DNA called (phosphate, n base, and ribose)

Nucleotide

What are the three core traits of DNA

DNA is a double helix
The strands are anti-parallel
Bases are complementary

How many base pairs are between each turn of the DNA helix

10 bases

What value do we use to express a single set of genes

1c

What is the human 1c value

3.2x10^9 unique base pairs

How long is 3.2 billion base pairs

3.5 feet

How is DNA compacted so tightly

DNA is supercoiled by topoisomerases

Chromatin

DNA with a protein "scaffold"

Histones

Have a net positive charge and are attracted to negatively charged DNA

Nucleosome

Are the fundamental repeating unit of chromatin

How many pairs of chromosomes do humans have

23

A picture of laid out chromosomes is called

A karyotype

Euchromatin

Uncoiled except during cell division, holds genes that are actively being replicated

Heterochromatin

Tightly packed DNA, generally inactive

constituative heterochromatin

Involved in maintaining structure and stability, centromeres and telomeres

facultative heterochromatin

Has the potential to become condensed, can uncoil if needed

Centromeres

Used by the cell during division in order to ensure each daughter cell gets a copy of the chromosome

Telomeres

Located at the end of the chromosome and tie off the chromosome

Telomerase

Adds new copies of telomeres in order to reinforce the end of the cell

Circular genome

Within mitochondria and chloroplasts, hundreds to thousands per cell
Usually inherited from the maternal side

heteroplasmic cells

Cells with chromosomes from both mom and dad due to random chance

homoplasmic cells

cells with chromosomes from only mom or dad

DNA replication is

semiconservative

What are the proposed methods of DNA replication

Conservative: One double helix is completely preserved and one is completely new
Dispersive: Each strand is a mix of new and old
Semi-Conservative: One double strand is conserved, one is new

DNA polymerase

Catalyzes the formation of phosphodiester bonds
Joins the 3'-OH bonds to the 5' phosphate

Which direction is DNA synthesized

5' to 3'

5 Key elements to each replication fork

Helicase Unwinds DNA
SSBP to protect ssDNA
Gyrase to remove strain ahead of fork
Primase to synthesize RNA primer
DNA polymerase

Key features of DNA replication in Eukaryotes

Initiated by RNA primers
Occurs in the 5' to 3' direction
Semiconservative

Packaging of newly replicated DNA

Histones must first disassemble to allow DNA synthesis
Synthesis of new histones is coordinated with DNA
Then must reassemble DNA

Polymerase details

Polymerases have 3' to 5' exonuclease acivity

What are the phases of the cell life cycle

G1 - Maintenance and preps RNA for S phase
G0 - Static phase that prevents the cell from replicating
S - DNA untwists and replicates
G2 - DNA condenses
Mitosis

Mitosis vs. Meiosis

Mitosis: two identical daughter cells
Meiosis: four unique daughter cells

What are the stages of Mitosis

interphase, prophase, metaphase, anaphase, telophase, cytokinesis

Prophase

Chromosomes condense, sister chromatids become detectable

Metaphase

Chromosomes arrange on the metaphase plate
Microtubules form from centromeres to kinetochore

Anaphase

Sister chromatids split
Chromosomes move to opposite ends of the cell

Telophase

Sister chromatids arrive at opposite ends of the cell
Nuclear membrane reforms
Chromosomes lengthen and uncondense

In which phase of meiosis does crossing over occur

Prophase 1

Independent assortment

2n possible combinations of chromosomes
Chromosomes split between daughter cells randomly

Does DNA or RNA have the 2'-OH

RNA

Does DNA or RNA degrade faster

RNA

Which direction is RNA synthesized

5' to 3'

What are the types of RNA

Messenger RNA
Transfer RNA
Ribosomal RNA
Small Nuclear RNA

tRNA

Translator molecule - speaks both DNA and RNA
step loop structure

rRNA

Makes the ribosome
Made of two subunits, large 28s and small 18s

What is the central dogma of genetics

DNA -> RNA -> Protein

What are the three components of the gene

Promoter, coding region, and the terminator

Promotor

Section that transcription machinery recognizes and binds to

Terminator

Specific sequence that indicates transcription should stop

Types of promotors

Core and regulatory

Core promotor

Required for any transcription
Site where basal machinery binds
TATA box
Transcription and regulatory factors bind here

Proteins

Functional molecules of the cell
Made of the 20 Amino Acids
Amino end and Carboxyl end

Protein Structure

Primary: AA sequence
Secondary: Interactions between AA
Tertiary: Structures made after 3D folding
Quaternary: Polypeptide interactions

Domains

Discrete groups of AA's that form a separate functional unit

Codon

3 base sequence that codes for an AA

Why are there only 20 amino acids

Some codons code for the same amino acid

What is significant about the AUG codon

It is the start codon

Which base of the codon can vary the most

The third base, this is called wobble

What are the three stop codons

UAG (Amber)
UAA (Ochre)
UGA (Opal)

What makes proteins

Ribosomes

What are the four phases of tRNA

tRNA Charging - binding tRNA to AA
Ignition - start of translation
Elongation - synthesis of polypeptide chain
Termination - ending synthesis

aminoacyl-tRNA synthetase

Attaches an amino acid to a tRNA, specific to a particular amino acid

Mutation

inhereted change in genetic information

Somatic mutation

A mutation that occurs post conception

Germ-Line mutation

Mutations passed down from generations

Types of Mutations

Base Substitution: alteration of a single nucleotide
Transitions: Substitution of a purine for a purine
Transversions: Substitution of a purine for pyrimidine

Indels

Insertion or deletion of one or more bases, can cause frameshift

Replicative mutation

The wrong base gets included during replication

Depurination

Loss of a purine base from a nucleotide

Deanimation

Loss of an amino (NH2) group

Mutagen

Environmental agents that increase the likelihood of mutations

What are the four steps for DNA repair

Detection
Excision
Polymerization
Ligation

Mismatch repair

Repairs a replication error that involves a misplaced base

Direct Repair

Restores the original structure of an altered nucleotide

Base Excision repair

DNA repair that first excises modified bases and then replaces the entire nucleotide

Nucelotide Excision repair

enzymes cut out and replace damaged stretches of DNA

fuark

yeah.