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PG 30-32 GENETICS. NOTES AND VOCABULARY. Genetics - the study of heredity . Heredity - a set of characteristics received from parents. Raising useful plants and animals . Prevention and treatment of diseases . Discovering the secrets of life on Earth. Solving crimes .

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pg 30 32 genetics

PG 30-32GENETICS

NOTES AND VOCABULARY

slide2

Genetics - the study of heredity.

  • Heredity - a set of characteristics received from parents.
uses for genetics

Raising useful plants and animals.

  • Prevention and treatment of diseases.
  • Discovering the secrets of life on Earth.
  • Solving crimes.
USES FOR GENETICS
gregor mendel

Known as the “father of genetics.”

  • Was both religious and scientific.
  • Introduced this branch of science to the world by cross-breeding plants, studying traits being passed along, and producing hybrids.
Gregor Mendel
definitions

True-breeding (purebred) - an organism with parents having the same traits.

  • Hybrid - an organism with parents having different traits.
  • Genes - parts of chromosomes that “carry” traits.
  • Alleles - different forms of a gene.
DEFINITIONS
alleles

Dominant - an allele that excludes the recessive form.

  • Recessive - an allele that is not expressed in the presence of a dominant allele.
  • AA - HOMOZYGOUS DOMINANT (same big)
  • Aa - HETEROZYGOUS (AKA: CARRIER - an organism that “carries” a recessive gene that is not expressed.) (different alleles)
  • aa - HOMOZYGOUS RECESSIVE (same small)
ALLELES
what is the difference between phenotype and genotype

Phenotype - displays the physical form of a trait.

      • Only what you can see when you look at an organism.
  • Genotype - displays the genetic form of a trait.
      • Only what the genes express…you may not be able to tell.
What is the difference between phenotype and genotype?
punnett squares

Punnett Square - a process used to determine the probability of offspring traits.

  • Probability - studies the likelihood of occurrence of random events.
  • Monohybrid - comparing one trait in a Punnett square.
  • Dihybrid - comparing two traits in a Punnett square.
PUNNETT SQUARES
more definitions

Multiple alleles - a type of gene that is determined by more than 2 alleles.

  • Complete dominance - a heterozygous condition in which both alleles are partially expressed. This results in an intermediate phenotype.
  • Incomplete dominance - a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype.
  • Codominance - a condition in which both alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other.
MORE DEFINITIONS
last definitions

Polygenic traits - traits for which the phenotype (appearance) depends on alleles in multiple genes.

  • Sex-linked traits - traits associated with a gene that is carried only by the male or female parent.
  • DNA fingerprinting - a technique to distinguish between individuals of the same species using only samples of their DNA.
LAST DEFINITIONS!!!
three conclusions to his research
Three Conclusions to His Research
  • Principle of Dominance and Recessiveness

One allele in a pair may mask the effect of the other

  • Principle of Segregation

The two alleles for a characteristic separate during the formation of eggs and sperm

  • Principle of Independent Assortment

The alleles for different characteristics are distributed to reproductive cells independently.

mendelian genetics
Mendelian genetics
  • Character (heritable feature, i.e., fur color)
  • Trait (variant for a character, i.e., brown)
  • True-bred (all offspring of same variety)
  • Hybridization

(crossing of 2 different true-breds)

  • P generation (parents)
  • F1 generation (first filial generation)
  • F2 generation (second filial generation)
  • Testcross: breeding of a recessive homozygote X dominate phenotype (but unknown genotype)
how can the chances of an offspring s traits be determined
How can the Chances of an Offspring’s Traits be Determined?
  • BY USING A PUNNETT SQUARE
  • Get out your Guinea Pig Dihybrid Cross
  • I will call up students to fill in one square on the example dihybrid cross on the board until we complete the problem.
what about 2 traits
What about 2 Traits?
  • BbLl x BbLl
  • The Gametes contain one of each of the alleles. (BL).
  • Each of the offspring contain four alleles exactly like the parents.(BbLl).
  • Notice the number of possible offspring has increased.
  • The phenotypic ratio is 9:3:3:1
now on your own
Now on your own…

Work the Dihybrid Crosses on your own.

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