Download Chapter 5 - Genetics, Sections 1, 2, 3 STUDY GUIDE

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Chapter 5 - Genetics, Sections 1, 2, 3
STUDY GUIDE
Lesson 1 – Mendel and His Peas
cross-pollination
heredity
dominant trait
one
genetics
recessive trait
Gregor Mendel
self-pollination
two
heredity
Passing of traits from parents to offspring
genetics
Study of how traits are passed from parents to offspring
Dominant trait
Genetic factor that blocks another genetic factor
Recessive trait
Genetic factor that is blocked by the presence of a dominant factor
Gregor Mendel
Studied heredity using pea plants.
***To observe how a trait was inherited, the above man controlled which plants pollinated other
plants. Pollination in pea plants occur in two ways.
Self-pollination
Type of pollination that occurs when pollen from one plant lands on the
pistil of a flower on the same plant.
Cross-pollination
Type of pollination that occurs when pollen from one plant reaches the
pistil of a flower on a different plant.
2
After analyzing the results of the experiments, the above man concluded
that _____ genetic factors control each inherited trait.
1
He also proposed that when organisms reproduce, each reproductive cell
contributes _____ factor for each trait.
Lesson 2 – Understanding Inheritance
alleles
codominance
environment
gene
genotype
heterozygous
homozygous
incomplete dominance
multiple alleles
pedigree
phenotype
polygenic inheritance
Punnett square
***Scientists discovered that inside each cell is a nucleus which contains chromosomes. Each
chromosome can have information about thousands of traits.
gene
A section of a chromosome which codes for one trait.
alleles
The two different forms of a gene. EXAMPLE: Pea plants can have two
purple alleles, two white alleles, or one of each allele.
genotype
The pair of alleles for a trait. EXAMPLE: BB, Bb, bb
phenotype
The outward expression (or physical appearance) of genetic traits.
EXAMPLE: brown and blue eye color
***An organism’s genotype determines its phenotype.
environment
An organism’s _______________ can also affect its phenotype.
EXAMPLE: Genes affect a person’s chances of having heart disease.
However, what a person eats and the amount of exercise he or she gets
can influence whether heart disease will develop.
homozygous
When the two alleles of a gene are the same. EXAMPLE: BB, bb
heterozygous
When the two alleles of a gene are different. EXAMPLE: Bb
Punnett square
A tool used to predict outcomes of genetic crosses. It shows you all the
ways in which alleles can combine.
pedigree
A diagram showing the traits of genetically related family members.
***For pea plants, the presence of one dominant allele produces a dominant phenotype.
However, not all allele pairs have a dominant-recessive interaction.
Incomplete dominance
Produces a blend of the parents’ phenotypes.
codominance
When both alleles can be observed in the phenotype.
Multiple alleles
Genes that have more than two alleles. EXAMPLE: human ABO blood
type – Type: A, B, O, and AB
Polygenic
When multiple genes determine a phenotype. EXAMPLE: eye color, skin
inheritance
color
Apply what you know.
Understanding Inheritance I
A farmer who raises vegetables wants to cross two types of corn plants. One type is a
homozygous plant with red kernels and the other is a homozygous plant with white kernels.
1. If red kernels are dominant, what letter would be used to represent the alleles?
__R____
2. What is the genotype of the parent who is a homozygous plant with red kernels?
__RR____
3. What is the genotype of the parent who is a homozygous plant with white kernels?
rr____
4. Create a Punnett square to predict the offspring the farmer should
expect.
5. List all the possible genotypes.
Rr__________________________________________
6. List all the possible phenotypes. red kernels
7. What are the chances of an offspring with red kernels? __4__ out of __4__ or
___100__%
8. What are the chances of an offspring with white kernels? _0___ out of _0___ or
_0____%
Understanding Inheritance II
The ozmox is a fictional creature with a variety of traits. Study the list of ozmox alleles
for the seven traits below. Then look at the genotypes of a particular ozmox named
Glork. Using that information, write the Glork’s phenotype for ach trait on the lines
provided.
Ozmox alleles:
Glork’s Phenotype for each trait:
Hair – shaggy (S); short-haired (s)
Hair: shaggy (heterozygous)
Nose – orange (O); green (o)
Nose: green (homozygous)
Tail – long (L); stubby (l)
Tail: long (homozygous)
Teeth – pointed (P); rounded (p)
Teeth: pointed (heterozygous)
Claws – curved (C); straight (c)
Claws: straight (homozygous)
Eyes – red (R); blue (r)
Eyes: blue (homozygous)
Ears – big (B); small (b)
Ears: big (homozygous)
Glork’s genotypes: Ss, oo, LL, Pp, cc, rr, BB