Show Menu
Cheatography

AP Bio Unit 5: Heredity Cheat Sheet by

AP Bio Unit 5: Heredity

Allele

altern­ative forms of a gene found on the same locus on a chromosome

Homozygous

2 identical alleles
BB (homoz­ygous dominant)
bb (homoz­ygous recessive)

Law of Segreg­ation (Random Fertil­iza­tion)

two copies of each hereditary factor (allele) segregate
offspring acquire one factor from each parent

Crossing Over

the reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis

Codomi­nance

blood groups
both alleles are expressed in the hetero­zygote
neither is dominant or recessive, but there is no blending

Pedigree Analysis

pedigree: family tree
males: squares
females: circles
shaded: showing exhibited trait
half shaded: carrier

Nature vs. Nurture

nature: geneti­cally determined
nurture: enviro­nme­ntally determined

Genes Inherited Located on Sex Chromo­somes

in humans:
~ females: XX
~ males: XY
examples of sex linked disorders:
~ duchenne muscular dystrophy
~ hemophilia
~ colorb­lin­dness

Calculate Recomb­ination Frequency

if RF is >50%, the traits are considered to be indepe­ndently assorted and on DIFFERENT chromo­somes
if RF is <50%, the traits are on the SAME chromosome (any variants from the parent type are due to crossing over)

Asexual Reprod­uction

two identical cells
"­clo­nes­"

Examples of Asexual Reprod­uction

Fission: bacteria
Fragme­nta­tion: starfish
Budding: coral

Terms

haploid: cells that contain a single set of chromo­somes in an egg or sperm cell (23 gametes)
diploid: two complete sets of chromo­somes (46 somatic)
triploid: Extra set of chromo­somes (69 chromo­somes)

Why are triploid plants seedless?

3 sets of chromo­somes make it very unlikely for meiosis to succes­sfully produce spores and gameto­phytes. Uneven number of chromo­somes that won’t pair correctly

Meiosis Results

4 haploid cells
not geneti­cally identical

Mitosis vs. Meiosis

simila­rities:
~ prophase, metaphase, anaphase, telophase (pmat)
~ cell division
~ cytoki­nesis: complete division of cytopl­asmic contents
differ­ences:
~ mitosis: single set of divisions
~ meiosis: two divisions
~ mitosis: production of 2n cells
~ meiosis: production of 1 n cells
~ mitosis: production of 2 cells
~ meiosis: production of 4 cells

Vertical Gene Transfer

parent to daughter cell
 

Dominant

a trait is expressed when dominant allele is present
capital letter (B)

Hetero­zygous

one dominant and one recessive allele
aka hybrids or carriers
Bb

Law of Indepe­ndent Assortment

hereditary factors (alleles) assort into gametes indepe­ndently from one another (every combin­ation)

Genetic Variation

crossing over
indepe­ndent assortment
random fertil­ization

Epistasis

different genes can interact to control the phenotypic expression of a single trait
nonallelic genes affect one another

Test Cross Image

X-Inac­tiv­ation in Females

barr bodies
DNA methyl­ation

Gene Linkage (Linked Genes)

genes that are on the same chromosome
usually linked genes will be inherited together (unless separated by crossing over)
exhibit recomb­ination freque­ncies less than 50%

Recomb­ination Frequency Equation (x100%)

Sexual Reprod­uction

gametes (sperm and egg)
two parents

Examples of Sexual Reprod­uction

internal fertil­iza­tion: humans, sharks, turtles
external fertil­iza­tion: frogs, many fish
hermap­hro­dites: most worms, flowering plants
pollin­ation: flowers

Meiosis

reduces the chromosome number
1) Interphase I
2) Prophase I
~ synapsis: the lining up of homologous chromo­somes
~ chiasma: exchange of genes between non sister chromatids
~ crossing over: results in recomb­ination of genes so they assort indepe­ndently
3) Metaphase I
~ lining up of homologous chromo­somes
4) Anaphase I
~ indepe­ndent assortment
5) Telophase I and Cytoki­nesis I
6) Prophase II
7) Metaphase II
8) Anaphase II
9) Telophase II and Cytoki­nesis II

Nondis­jun­ction in Meiosis 1(left) and 2(right)

Horizontal Gene Transfer

donor to recipient cell
transf­orm­ation (uptake of external DNA (plasmid))
transd­uction (virus -> bacteria)
conjug­ation (bacteria -> bacteria)
 

Recessive

a trait is masked in the presence of a dominant allele
lower case letter (b)

Phenotype

physical charac­ter­istic of a trait
color, size

Genotype

genetic makeup of the chromosome
letters (B, b, G, g)

Incomplete Dominance

neither allele is completely dominant
hybrids are in between the homozygous traits
blending

Polygenic Inheri­tance

mode of inheri­tance in which additive effects of two or more genes determines a single trait
quanti­tative characters that vary in degree
AABBCC: dark
aabbcc: light

Disorders

Dominant disorders:
~ anchon­dra­plasia (dwarfism)
~ huntin­gton's (late acting lethals)
Recessive disorders:
~ cystic fibrosis
~ tay-sachs
~ sickle cell

Barr Bodies Image

Calculate Chi Square

if we accept the null hypothesis (1:1:1:1), then the genes indepe­ndently assort on DIFFERENT chromo­somes
if we reject the null hypothesis (1:1:1:1), then the genes are on the SAME chromosome

Asexual vs. Sexual Reprod­uction

 
Advant­ages:
Disadv­ant­ages:
Asexual:
do not have to find a mate or expend energy to find a mate
not much genetic variation
Sexual:
genetic variation
must find a mate and expend energy to find and/or court a mate

Meiosis Image

Crossing Over Image

 

Comments

No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          AP Biology Unit 2: The Cell and Cell Membrane Cheat Sheet
          AP Biology Unit 1: Biochemistry Cheat Sheet

          More Cheat Sheets by julescrisfulla

          AP Bio Unit 1: Chemistry of Life Cheat Sheet
          AP Bio Unit 2: Cell Structure and Function Cheat Sheet
          AP Bio Unit 3: Cell Energetics Cheat Sheet