Unit 7 - genetics

Unit 7 - genetics

By Johnica Hanke

Gametes are sex cells. Eggs in females. Sperm in males.

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​Gametes

Haploid

Sex cells (gametes) are haploid, meaning, they have only one copy of every chromosome. In humans that equals 23 chromosomes.

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Body cells (somatic cells) are diploid, meaning, they have 2 copies of every chromosome. In humans that is 23 pairs of chromosomes or 46 total.

this refers to all types of body cells: skin, muscle, liver...

Diploid

Therefore the purpose of meiosis is to produce gametes, the sperm and eggs, with half of the genetic complement of the parent cells. In the figures below, pink represents a genetic contribution from mom and blue represents a genetic contribution from dad.

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Meiosis

Multiple Choice

Meiosis is the division of ____.

• gametes

• somatic cells

• stem cells

• embryos

Multiple Choice

Sex cells: eggs in females and sperm in males are also called ____.

• somatic cells

• gametes

• embryos

• zygotes

A pair of homologous chromosomes contains chromosomes of similar length, gene position, and centromere location.

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Homologous Chromosomes

• Crossing over is the exchange of chromosome segments between homologous chromosomes.

• The purpose of crossing over is to recombine genes for more genetic diversity of the offspring ​

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Crossing Over

Multiple Choice

Paired chromosomes that have similar gene placement and length are called _____ chromosomes

• homozygous

• diploid

• homologous

• haploid

Multiple Choice

Recombination occurs in the genes of homologous chromosomes during the process of crossing over. The purpose of this process is

• to decrease the distance between genes

• to increase the distance between genes

• to decrease genetic diversity

• to increase genetic diversity

Multiple Choice

Recombination/Crossing over occurs in ____

• somatic cells

• gametes

• stem cells

• line for lunch

Gregor Mendel researched on purebred pea plants.

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Mendel’s data revealed patterns of inheritance.

​The Father of Genetics

Multiple Choice

Who researched genetics using pea plants? We also call him "the Father of Genetics". He has 3 laws: Law of segregation, law of independent assortment and law of dominance.

• Lebron James

• Teddy Roosevelt

• Gregor Mendel

• Samuel Martin

Allele /əˈlēl/

Different versions of the same trait. For example: Hair color (trait) could be brown (B) or blonde (b)

Dominant Allele

A dominant allele is a variation of a gene that will produce a certain phenotype, even in the presence of other alleles. It will dominate over the other alleles present. When working with genotypes the dominant allele will be represented with a capital letter.

Recessive Allele

A recessive allele is a variation that does not create a phenotype if a dominant allele is present. In a dominant/recessive relationship between two alleles, the recessive allele's effects are masked by the more dominant allele. If no dominant allele is present the recessive phenotype will appear.

Recessive alleles will be represented with lowercase letters. ​

Multiple Choice

Which of the following represents a dominant allele?

• B

• q

• b

• a

Multiple Choice

Which of the following represents a recessive allele?

• B

• Q

• b

• A

Phenotype is a combination   of genotype and environment.

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Phenotype

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Multiple Choice

An organism has brown hair (Bb). Brown hair is the organism's ___.

• Phenotype

• Genotype

Multiple Choice

An organism has brown hair (Bb).

Bb is the organism's ___.

• Phenotype

• Genotype

• The Punnett square is a grid system for predicting all possible genotypes resulting from a cross.

  • The axes represent the possible gametes of each parent.

  • The boxes show the possible genotypes of the offspring.

Punnett Squares​

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Monohybrid

• Monohybrid crosses examine the inheritance of only one specific trait.

Some text here about the topic of discussion

Two of the same dominant alleles for a trait.

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For example: RR ​

homozygous dominant

Two of the same alleles that are the recessive version of a trait.

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For example: rr ​

​​homozygous recessive​

Two different alleles for the same trait.

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For example: Rr ​

heterozygous

A dihybrid cross involves two traits.   

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Dihybrid Cross

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Multiple Choice

Which example is NOT an outcome of the environment modifying a phenotype? 

• the changing of the color of an animal’s fur as the temperature changes

• the increased intelligence of a person who attended school for many years

• the pink-flowered snapdragons that result from crosses between red-flowered and white-flowered snapdragon plants

• the very short stature of a kind of tree that grows at a high altitude in comparison with the same kind of tree growing at a lower altitude

Multiple Choice

What is the phenotypic ratio of a monohybrid cross between two heterozygous parents? 

• 3:1

• 1:2:1

• 9:3:3:1

• 1:2:2:1

Multiple Choice

What is the name for a cross that examines the inheritance of two traits?

• dihybrid

• monohybrid

• codominance

• incomplete dominance