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FOB exam 3 Cheat Sheet (DRAFT) by

Foundations of Biology EXAM 3

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Phases of the cell cycle Mitosis

Prophase
Chromo­somes condense and spindle aparatus forms
Promet­aphase
Kineto­chores assembled at centro­mere, 2 opposite sides connected to microt­ubles
Metaphase
Lined up on imaginary metaphase plate. Polar microt­ubles extend from each spindle, overlap in middle, pole-pole connection
Anaphase
Cohesions are cleaved, daughters to opposite sides of cell. poles pulled apart
Telophase
Nuclear envelope reforms, chromo­somes begin to condence
Cytoki­nesis
Division of cytoplasm

Types of dominance

Incomplete dominance
Phenotypes are blended together
 
ex. pink flowers come from red and white allels
Co-dom­inance
Both phenotypes show up
 
ex. polka dots

Mitosis

Mitosis
When cells divide, two gentet­ically identical sister cells are their products
Uses
Somatic cells

G1 checkpoint

1.
Cells big enough
2.
Sufficient nutrients
3.
social signals present
4.
Cells undamaged

G2 checkpoint

1.
No errors in replic­ation
2.
Activated MPF (cyclin + CDK) present
3.
Undamaged

Metaphase checkpoint

1.
Chromo­somes attatch to spindles
2.
Chromo­somes properly segregated
3.
MPF absent

Mechanisms of cell cycle progre­ssion

Nucleotide excision repair
1. Error detected in DNA by proteins
 
2. DNA nicking (cut at both sides of damage)
 
3. Helicase unwinds and removes region with damaged bases
 
4. DNA polymerase fills gap with undamadged strand as template
 
5. Nuleotide linkage (DNA ligase links the strand into esisting strand.
 
If sucessful continues past G1 checkpoint
P53 gene
Creates CDK inhibitors if the cell is damaged so if cyclin is still present, CDK can still say no if damaged
UVRA
recgonizes DNA damage, signals to start repair, if damage cant be repaired cell wont divide anymore.
recA
Facili­tates DNA repair

Genes on X-chro­mosome

The X chromosome is larger
it holds most all of the sex-linked traits
In females
Females have 2 copies of X chromosome
 
When sex linked traits are recessive they would need 2 copies to express the mutation
In males
Males only have one X-chro­mosome
 
Males only need 1 copy of recessive X-linked trait to express the mutation

Segreg­ation and Indepe­ndent assortment

Law of segreg­ation
Each diploid parent forms a haploid gamete
Indepe­ndent assortment
Allels of different genes seperate indipe­ndently of eachother to form gametes
 

Epistasis

Epistasis
The expression of one gene influences or masks the expression of another gene
Ex.
Fur color in golden retrievers

Map distance for F2 generation

Greater than 50 map units
Indepe­ndently assorting

Indepe­ndent assortment

Linked genes
Do not follow rules of indepe­ndent assortment
 
Too close together on chromosome to seperate
Closer genes are
More likely they are linked
Indepe­ndent assortment
occurs between chromo­somes not within

Reciprocal vs Test cross

Reciprocal cross
The cross between a male with one phenotype and a female with another and then flipping
 
Determines if sex plays a role in inheri­tance
Test Cross
Dominant phenotype crossed with recessive genotype
 
Determines genotype of dominant phenotype

Genes arranged on chromo­somes within genome

Karyotype
# and visual appearance of gametes
Genes hold
Instru­ctions for making mRNA
Homologous chromo­somes
Same genes in same location, but different versions of gene
Allels
versions of genes
Genotype
Allels present
Gene locus
location of genes

Asexual vs Sexual reprod­uction

Asexual
Sexual
No variation, exact clones
More variation
Quicker
Slower
Binary fission
Humans
Mitosis
Meiosis

Importance of Telomeres

Protect from
important DNA being cut out
Everytime cell divides
become shorter
Replic­ation limit
prevents cancer
Why?
There is no 3' hydroxyl at end of lagging stand.
What?
G-rich series of repeats
Telomerase
elongates parental in 3' to 5' direction.

Both leading and Lagging strands

Single stranded binding proteins (SSBs)
Keep stands from attatching back together
Ligase
Fills in gaps or breaks in phosph­odi­ester bonds of backbone
Helicase
Seperares, unwinds double stranded DNA
Topois­omerase
Helps with stress on wound DNA, ex. Gyrase

DNA synthesis in lagging strand

Synthe­sized
in fragments (Okazaki fragments)
Initiated by
RNA polymerase
RNA polymerase
builds primers
DNA polymerase
replicates DNA off of primers
RNA primer
popped out of gaps and replaced with DNA polymerase

DNA synthesis in Leading strand

Synthe­sized
Contin­ously
Begins with
RNA primer
After RNA primer
DNA polymerase