UNIT D: Heredity & Populations

Question 1

Heredity

True Breeding

mendellion

Answer 1

plants that exibit the same characteristics generation after generation
(these plants are called the parental generation)

Question 2

Heredity

Why did Mendel work with garden pea plants?

Answer 2

1. variety of chracteristics (ex. wrinkled x smooth)
2. both self-fertalizing and cross-fertalizaing

Question 3

Mendel’s Laws of Heredity

Inherited Characteristics

Answer 3

Are controlled by genes that occur in pairs
(during cross fertilization each parent contributes one of its genes)

Question 4

Mendel’s Laws of Heredity

Law of Dominance

Answer 4

one factor or gene masks the effect of another
(Dominant = uppercase letter (A) , Recessive = lowercase letter (a) )

Question 5

Mendel’s Laws of Heredity

Law of Segregation

Answer 5

-a pair of genes, seperate or segregate during the formation of sex cells (gametes)
…
(Mendel thought that sex cells contain only one member of the pair of genes… with no knowledge of meiosis)

Question 6

Mendel’s Laws of Heredity

Law of Independent Assortment

Answer 6

the two alleles for one gene seperate (assort) independently of the alleles for other genes during gamete formation

Question 7

Genetic Terms

Genotype vs Phenotype

Answer 7

-geno. refers to the genes that an organism for a particular trait (TT, Tt, tt)
-pheno. refers to the observable traits of an individual (eg. tall or short)

Question 8

Genetic Terms

Homo vs. Heterozygous

Answer 8

Homo: same two genes (TT, tt)
Hetero: two diff genes (Tt)

Question 9

Genetic Terms

Alleles

Answer 9

two or more alternate forms of a gene
…
(each allele is located at the same position on one of the pairs of homologous (sister) chromosomes)

Question 10

Single Trait Inheiritance

Monohybrid Cross

Answer 10

combination of single contrasting traits (ex. RR x rr) using Punett square(s)

Question 11

Single Trait Inheiritance

Test Cross

Answer 11

a cross between an organism of unknown genotype and a homozygous recessive organism, used to determine the UNKNOWN genotype (parent w unknown genotype displays dominant trait) (Tt/TT x tt)

Question 12

Single Trait Inheiritance(?)

The Product Rule

Answer 12

The probability of two (or more) independent events occuring together can be found by multiplying the probabilities of the individual events
…
(ex. Hitchhikers thumb (hh).. in notes (pg 111), what is probability of first child having it(0.25), second child(0.25), first three children (0.25 x 0.25 x 0.25 = 1.56%) etc. times by the number of the first child by eachother per child) or times the probabilities togteher to get result ex. (normal thumb x girl)

Question 13

monohybrid crossing

Monohybrid Cross

Answer 13

a type of genetic cross where individuals with different variations of a single gene are mated.

This cross is used to study how a single trait is inherited from one generation to the next. The resulting offspring are called monohybrids.

(ex. Cc x cc, TT x Tt)

Question 14

Incomplete/Co-Dominance

Incomplete Dominance

Answer 14

• when two genes are equally dominant, tehy combine/blend to produce a new phenotype
  (ex. Red x White = Pink)
• either two letters are used to represent each allele or the same letter with superscript or subscript number or letters are used
• (ex. red could be R or R1 and white could be W or R2)

ex. snap dragon plant (CRCR x CWCW = CRCW)

Question 15

Incomplete/Co-Dominance

Co-Dominance

Answer 15

• is another type of non-mendelian dominance
• one allele does NOT mask the other rather BOTH exsisnt intermingled
• EX. a red bull and a white cow will produce a calf with intermingled red and white hair (called Roan)

( RR x WW = RW (roan))

Question 16

Multiple Alleles

How do you arrange multiple alleles?

Answer 16

• the order of dominance
• ex. (wild type > apricot > honey > white) (E1>E2>E3>E4)
• when in a punnette square:
• top: E1 E3
• side: E2 E4

pg 117

Question 17

Multiple Alleles

Blood types and how they’re written (ABO)

Answer 17

IAIB = type AB
IAIA / IA i= type A
IBIB / IB i= type B
ii = type O (no antigen)

Question 18

Enviromental Influence

Whats an example of enviromental influnece, and why does it occur/present?

Answer 18

-pigment in siamese cats is determined by temperature (born white, enzyme (tyrosinase) functions at cooler parts of body (feet, face, tail)…gene is only active in lower temperatures

Question 19

Sex Linked Inheiritance

What is sex-linked inheirtance? / example

Answer 19

• Sex linked trait: controlled by genes located on the sex chromosomes (typically X)
• represrnt the traits as superscript letters ex. (Xa Ya)
• males only have one X chromosome so this affects inheirintance (males cannot be carriers)
• women can be carriers and not express the trait/gene (es. X Xa)

Question 20

Sex Linked Inheirintance

Name some syndromes and other examples that can occur in relation to sex-linked inheirintance

Answer 20

• extra or missing chromosome (nondisjunction) ex. XXY = Klienfelters syndrome (AMAB)
• Barr Body: an inactive X chromosome that is tightly condensed (XXX… trisomy X (AFAB) no significant symptoms).
• Calico cats (cat version of . skin disorder “antidrotic ectodermal dysplasia)… expressing diffent alleles in diff parts of skin (heterozygous in feme (XRXR) (in activation causes patches…. this is why calico cats are typically female.

Question 21

Dihybrid Crosses

What is a Dihybrid Cross?

Answer 21

• crosses involving two traits
• ex. TT yy x tt YY = TtYy
• look at notes for big cross (TtYy x TtYy)

pg 124 in notes

Question 22

Polygenic Inherintance

Continuous Traits

Answer 22

• traits for which the phenotype vary gardually from one extreme to another (ex. height in humans, skin colour, weight/body comp., eye colour, hair type/length)

Question 23

Polygenic Inheirintnace

Polygenic Traits

Answer 23

• traits that are controlled by multiple genes
• ex. skin colour in humans or ear length in corn
• dominant alleles contribute to the trait and recessive traits do not
• polygenic traits much more variability in a population than single gene traits

Question 28

# Linked genes & chromosome mapping Linked Genes

Answer 28

- genes found on the same chromosome (wont be in diff. gametes) - do not assort independtly - "crossing over" occurs udring Prophase I (meiosis) -if a corssover occurs between two genes then the alleles will be on diff. chormosomes a cross over is more liekly to occur between genes that are father apart than closer together

Question 29

# chromosome mapping Chromosome Mapping

Answer 29

- the process of crossing over is used to dtermine the relative positionns of genes on a chromosome - measured in MAP UNITS: the distance between two genes (M.U. for short) | look at notes for examples (pg 128)

Question 31

# chormosome mapping Parental and Recombinant types (chormosome mapping)

Answer 31

include parental - (F1 individuals w chromosomes (phenotypes) identical to parents and recombinant types - (refer to offspring with gene combinations (phenotypes) different from those found in their parents.) the percent (which you find by adding up the percents ex. 5% + 5% = 10%) of the offspring that express this is called recombinant frequency)

Question 31

# Pedigrees Pedigree def

Answer 31

- a type of chart/family tree that uses symbols to show the patterns of relationships and traits in a family over many generations | pg 132

Question 31

# chormosome mapping recombinant frequencey equation?

Answer 31

Recomb. Freq. = Gene distnace (M.U.) = # of recomb. types / total # of offspring x 100 | pg 129, look at note examples/questions

Question 32

# Pedigrees in pedigrees, a disorder can be: | modes of inheirintance

Answer 32

- Autosomal (dom/reccesive) - Sex-Linked (dom/reccesive) (usually x-linked, y-linked rare and is from father to son)

Question 33

# Pedigrees Autosomal dominant

Answer 33

- heterozygotes are affected by the trait and an affected child must have at least one affected parent - trait is present in EVERY generation - (AA & Aa = affected, aa = unaffected) | look at notes diagram pg 132

Question 34

# Pedigrees Autosomal Recessive

Answer 34

- affected chikdren may have unaffected parents and that heterozygotes are not affected by the trait - trait frequently "skips" a generation - (rr = affected, RR & Rr = unaffected)

Question 35

# Pedigrees X-Linked Traits (recessive)

Answer 35

- males are much more likely to have the condition than females - females who are heterozygous for the condition (carriers) can pass on an allele - "recessive" can "skip" gnerations through female carriers (ex. X Xa, the mother herself unaffected, passes disorder on to son) | pg 133