1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each...

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1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from each parent 3. If two alleles differ, one is dominant, the other recessive 4. The two alleles for each character segregate (separate) during gamete production. Genetics: Review

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Transcript of 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each...

Page 1: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

1. Alternative versions of genes (alleles) account for variation in inherited characters

2. For each character, an organism inherits two alleles, one from each parent

3. If two alleles differ, one is dominant, the other recessive4. The two alleles for each character segregate (separate) during gamete production.

Genetics: Review

Page 2: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

F1 Generation

RR rr

Gametes

P Generation

F2 Generation Sperm

Gametes

Red White

R r

RrPink

R r

R r

R

r

RR Rr

rrRr

Eggs12

12

12

12

12

12

Variations in Mendel’s Laws

In incomplete dominance, F1 hybrids have an appearance in between the phenotypes of the two parents.

Page 3: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

Homozygousfor ability to make

LDL receptors

Severe diseaseMild diseaseCell

Normal

LDLreceptor

LDL

Homozygousfor inability to make

LDL receptors

HeterozygousHH Hh hh

GE

NO

TY

PE

PH

EN

OT

YP

E

Hypercholesterolemia•Dangerously high levels of cholesterol in the blood.•Is a human trait that is incompletely dominant.•Heterozygotes have blood cholesterol levels about 2X normal.•Homozygotes have blood cholesterol levels about 5X normal.

Variations in Mendel’s Laws

Page 4: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

BloodGroup

(Phenotype)Genotypes Red Blood Cells

O

A

B

AB

ii

IAIB

IBIB

orIBi

IAIA

or IAi

Carbohydrate A

Carbohydrate B

Variations in Mendel’s LawsMultiple Alleles

Page 5: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

Variations in Mendel’s Laws– Pleiotropy is the impact of a single gene on more than one

character.

Pleiotropy Multiple traits(e.g., sickle-celldisease)

Singlegene

Page 6: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

Variations in Mendel’s Laws

Page 7: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

*Epistasis

Example:

In Drosophila, gene:eyeless

*Black (B) is dominant to brown (b)*Second gene responsible for allowing pigment to be deposited in hair

C = presence, c = absence (colorless)

Variations in Mendel’s Laws

Page 8: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

Multiple genes

Polygenicinheritance Single trait

(e.g., skin color)

– Polygenic inheritance is the additive effects of two or more genes on a single phenotype.

Variations in Mendel’s Laws

Page 9: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

Variations in Mendel’s Laws

F1 Generation

P Generation

F2 Generation Sperm

AABBCC(very dark)

Eggs

aabbcc(very light)

AaBbCcAaBbCc

18

164 64

66415

6420

6415

646 1

64

18181818181818

18

18

18

18

18

18

18

18

Page 10: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

*Gene interactions

Variations in Mendel’s Laws

Page 11: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

Sex Linkage

*Sex chromosomes*Autosomes

Example: In Drosophila and all mammals

sex chromosomes designated as X and Y

XX=female

XY=male

*1909 Thomas Hunt Morgan

II III IV

XX

XY

or

Page 12: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

Any gene located on a sex chromosome is called a sex-linked gene.•Most sex-linked genes are found on the X chromosome.

Sex Linkage

Page 13: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

*Phenotype depends on environment and genes

Variations in Mendel’s Laws

Page 14: 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character, an organism inherits two alleles, one from.

How do we account for genetic variation?

*Independent assortment *Crossing over *Random fertilization

Independent Assortment:

Cross over:


CO-DOMINANT ALLELES: BLOOD TYPES. BOTH alleles are expressed, even when the genotype is heterozygous Both alleles are represented by capital lettersEX:

CO-DOMINANT ALLELES: BLOOD TYPES. BOTH alleles are expressed, even when the genotype is heterozygous Both alleles are represented by capital lettersEX:

Mendel’s hypotheses (to explain his results) 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character,

Mendel’s hypotheses (to explain his results) 1. Alternative versions of genes (alleles) account for variation in inherited characters 2. For each character,

Genetics Chapter 13. Traits, Genes, Alleles Genetics –Study of genes and ways they are inherited Genes –Internal factors –Provide instructions to plant.

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MENDEL AND THE GENE IDEA...2018/12/13  · MENDEL’S PRINCIPLES 1. Alternate version of genes (alleles) cause variations in inherited characteristics among offspring. 2. For each

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9.2 Experimental genetics began in an abbey garden...for variations in inherited characters. 2. For each characteristic, an organism inherits two ... Widow’s peak Straight hairline

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Multiple Alleles

Multiple Alleles

Genetic Crosses & Punnett Squares. Important Terms Dominant Trait : the trait that shows when two different alleles for the trait are inherited ex- tongue.

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tubman.wikispaces.compac… ·  · 2012-03-17The scientific study of heredity is genetics. ... 14. A black cat and a ... Describe how alleles from different genes can be inherited

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5.2: Traits & Punnett Squares & Meiosismrsbotten.weebly.com/uploads/2/1/3/9/21399952/ch5.23-pun... · 2019-09-27 · CH 5 VOCABULARY Genotype: both inherited alleles together form

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What is genetics? Every sex cell has one allele for each trait. Genetics - the study of how traits are inherited through the interactions of alleles is.

What is genetics? Every sex cell has one allele for each trait. Genetics - the study of how traits are inherited through the interactions of alleles is.

What is Evolution? In biology, evolution is the change in the inherited traits (a.k.a. genes/alleles, genotypes/phenotypes) of species (or populations.

What is Evolution? In biology, evolution is the change in the inherited traits (a.k.a. genes/alleles, genotypes/phenotypes) of species (or populations.

Applications of Mendel. Dominant/Recessive For every gene/characteristic an individual possesses two inherited copies (alleles) One maternal, one paternal.

Applications of Mendel. Dominant/Recessive For every gene/characteristic an individual possesses two inherited copies (alleles) One maternal, one paternal.

BIOLOGY Topic 3 Topic 3. Topic Outline Chromosomes, Genes, Alleles and Mutations Chromosomes, Genes, Alleles and Mutations Chromosomes, Genes, Alleles.

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chapter two - AAAS Home · which means they carry two alleles for every gene (one inherited from the father and one from the mother); the two alleles in a given pair may be identical

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Review What is an allele? What is a gene? Define phenotype. Define genotype. Each person inherits two Each person inherits two alleles for each gene, one.

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Blood Genetics Multiple Alleles - More than 2 alleles, BUT … A BO You will only inherit 2 of the 3 alleles.

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Lethal Recessive Alleles

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Genetic Mutations & Pedigrees. Alleles that code for defective proteins can cause mutations & even deadly disorders, which are passed on to us as inherited.

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Genetics in Humans Marie Černá. Monogenic inheritance (Mendelian genetics) – 1% –single gene For each gene, an organism inherits two alleles, one from.

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