Mendelian Inheritance Terms & Definitions | Biology Study Set

Theory of Pangenesis

- proposed by Hippocrates

- "seeds" are produced by all parts of the body

- collected in reproductive organs

- then transmitted to offspring at the moment of conception

Theory of preformation

Stated that the fertilized egg contains a complete miniature adult, called a homunculus

- is incorrect

Blending Theory of Inheritance

-Factors that control hereditary traits are malleable

-They can blend together from generation to generation

Gregor Johann Mendel

Father of genetics

- chose garden pea to study the natural laws governing plants hybrids

Laws of Inheritance

law of dominance,

law of segregation,

law of independent assortment

gardening pea (Pisum Sativum)

- existed in several varieties with distinct characteristics

- structure allowed for easy crosses where the choice of parental plants could be controlled

Hybridization

taking chromosomes from 2 different individuals and fusing them together

- purple plant x white plant

Hybrids

Offspring of crosses between parents with different traits

Two types of crosses

- self-fertilization

- cross fertilization

self-fertilization

When pollen fertilizes eggs from the same flower

- occurs in peas due to a modified petal isolates the reproductive structures

cross-fertilization

Pollen and egg are derived from different plants

- required removing and manipulating anthers

cell fertilization

characters

morphological characteristics of an organism

- Ex: eye color

what characters that mendel study

- height

- flower color

- flower position

- seed color

- seed shape

- pod color

- pod shape

trait/variant

the specific properties of a character

- Ex: blue eyes

what variants did Mendel study

Tall/dwarf = height

purple/white = flower color

axial/terminal = flower position

yellow/green = seed color

round/wrinkled = seed shape

green/yellow = pod color

smooth/constricted = pod shape

emperical approach

evidence based method that draws on observation and experimentation

true-breeding

Organisms that, when reproducing, create offspring of all the same variety.

(usually involves homozygous genes)

P generation

Parental generation, the first two individuals that mate in a genetic cross

Homozgous Dominant

Both alleles (factors) for a trait are the same and dominate (AA)

homozygous recessive

Both alleles (factors) for a trait are the same and are recessive (aa)

- are not functional

heterozygous dominant

two different genes; Aa

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

monohybrid cross (single factor cross)

A cross between individuals that involves one pair of contrasting traits (one gene, one character)

phenotypic ratio

the ratio of phenotypes that could appear in offspring

3:1 (P_ dominant)

genotype ratio for monohybrid cross

1:2:1 (HD, HD, HR)

genes vs alleles

Genes: the factors that are passed from one parental generation to the next.

Alleles: Different forms of a gene.

model organisms

species that are easy to raise in the lab and use in experiments

dyhybrid cross

a cross between 2 genes that have different alleles for the same gene

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Phenotypic ratio

9:3:3:1 ratio

Branch Diagram

diagram that considers contrasting pairs of traits separately then combines results based on a set of assumptions

law of independent assortment

genes separate independently of one another in meiosis

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- during gamete formation, the segregation of any pair of hereditary determinants is independent of the segregation of other pairs

Law of Segregation

pairs of genes separate in meiosis and each gamete receives one gene of a pair

- allelic pair that separates during meiosis

test cross

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

loss-of-function allele

a mutant allele that does not produce a functional product

- usually occurs on recessive alleles

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

pedigree analysis

Chart showing one trait being carried over many generations

Pedigree symbols

Squares are male. Circles are females. Shaded means you have disease. Half shaded means you are a carrier

modes of inheritance

Autosomal dominant

Autosomal recessive

X-linked dominant

X-linked recessive

Y-linked

autosomal dominant

anyone affected must have al least 1 affected allele

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- R = affected (RR or Rr)

- r = unaffected (rr)

autosomal recessive

anyone affected must have the homozygous recessive genotype

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- R = Unaffected (RR pr Rr)

- r = affected (rr)

X-linked dominant

Father passes its XD to all his daughters

- does not skip generations

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- father= XDY

- daughters= XDX

X-linked recessive

carried by females and affects males (all sons)

- can skip a generation (but doesn't have to

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affected

- son has to have XRY

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unaffected

- men has to have XY

- women have to have XXR

Y-linked

only males affected

- passed on from generation to generation

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- A = affected

- a = unaffected

Recessive models of inheritance

if you see any skipping then its a recessive

- remove any dominant models

cystic fibrosis (CF)

autosomal recessive mutation

- the gene encodes a protein called the cystic fibrosis transmembrane conductance regulator (CFTR)

CFTR

- protein regulates chloride ion transport across the cell membrane

- mutant alles create an altered CFTR protein that causes ion imbalance

probability prediction (requirements)

the accuracy depends on the size of the sample

Probability Equation

(Number of desired outcomes) / (Total number of outcomes)

expected outcome vs observed outcome

observed: the results you see and record

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expected: the results you expect to see (forecasted results)

Product Rule

the probability that two or more independent events will occur is equal to the product of their individual probabilities

- when reading a question the word and signifies product rule

sum rule

probability of either of two mutually exclusive events occurring is the sum of their individual probabilities

- will always equals 1

binomal expansion equation

represents all of the possibilities for a given set of unordered events

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P= probability that the unordered outcome will occur

n = total number of events

X = number of events in one category

p = individual probability of x

q = individual probability of other category

Chi-square test

method used to determine goodness of fit

- how close the observed data are to those predicted from a hypothesis

- dose not prove if a hypothesis is correct

chi square equation

(observed-expected)^2/expected

Low chi square values

high probability that the observed deviations could be due to random sampling errors

High chi square values

low probability that the observed deviations are due to random chance alone

- less than 5%

- usually rejects null hypothesis