Genetics and Heredity Outline
Name ______Homeroom ______
Genetics and Heredity Outline
What is Genetics?
n Traits are ______.
¡ Same hair color, eye color, or skin color.
n Genetics is the science of ______.
n Heredity is the study of the way ______are passed on from ______to ______.
Variation
n The ______an organism inherits is determined during the life process of ______.
n More ______ (differences) are found in ______reproduction than by ______reproduction.
n In sexual reproduction, the offspring ______its parents but is also ______from them.
Species and Chromosome Number
n The ______number (species chromosome number) is the same from ______to generation within an ______or species.
n Every ______will have a different ______number.
¡ Human =
¡ Crayfish =
¡ Dog =
¡ Cat =
¡ Pea =
¡ Fruit fly =
Chromosome Arrangement
n In a cell, ______are arranged in ______.
n A photograph or chart of ______arranged in pairs is called a ______.
Gregor Mendel
n Today’s knowledge about ______is a result of genetic studies started by ______ in the middle 1800’s.
n Because of his work, he is called the “father of ______.”
n Mendel did not know about ______, but thought that certain “______” were responsible for ______passed from parents to offspring.
The Gene-Chromosome Theory
n This theory states that ______(found in the ______of the cell) are made of small units called ______.
n Genes carry ______information and are found at specific locations along ______.
Alleles
n ______are pairs of ______that carry the ______traits and are found at the ______locations on pairs of ______.
n Each chromosome may contain several hundred ______.
Inheritance of Traits
n During ______, the male and female parents each contribute genetic information (______) to the ______(fertilized egg).
¡ One-half of its genetic information is from its ______parent and the other ______from its ______parent.
n ______traits are carried in ______.
Mendel’s Experiments
n Gregor ______conducted ______experiments using common garden pea plants.
n Mendel ______(mated) large numbers of plants.
n Mendel concluded that there were ______that always appeared (were expressed) when they were present in an organism.
n The purebred plants are called the ______(P) generation.
n The ______of a cross between two parent (P) generation plants are called the first filial (F1) generation.
n The trait that always appears when it is present is called the ______ trait.
n The trait that is hidden by the dominant trait is called the ______ trait.
Genetic Terms
n ______Trait - Both ______for that ______are the ______.
¡ A pea plant with two genes for tallness.
n ______Trait - Both ______for that trait are ____ the same.
¡ A pea plant with one gene for tallness and one for shortness.
n ______ - The ______makeup of an organism.
n ______ - The external ______of an organism.
¡ For example, an organism that looks tall can have a genotype that is pure tall or hybrid tall. This is because whenever the dominant trait is present, the organism expresses (shows) the dominant trait.
Punnett Squares
Try This Punnett Square
In roses, red is dominant over white.
1. What letter represents the red gene?
2. What letter represents the white gene?
3. Cross two heterozygous red roses.
Describe the phenotype of the offspring.
A Dihybrid Cross
n In mice, black is dominant over tan and short tails are dominant over long.
n Write the genotype for a heterozygous black, short- tailed mouse.
B = black
b = tan
S = short tails
s = long tails
n
What are the possible gametes for this mouse?
Each gamete must have one “B” and one “S”
n Describe the phenotype of
the offspring.
Gene Linkage
n Today, we now know that ______are not all inherited independently of each other.
n Scientists have found that ______that are located on the same ______tend to be inherited ______.
n Traits located on the same chromosome are said to show ______.
Crossing-Over
n Although linked genes are generally inherited ______, they can become separated by ______, which may occur during a stage of ______.
n During this stage, the four chromatids sometimes ______around each other.
n As they separate, the chromatids may ______, exchange segments, and ____.
Incomplete Dominance
n Incomplete dominance or ______inheritance occurs when the offspring shows traits that are a ______or _____ of the two parents.
Inheritance of Sex
n Your ______(male or female) was determined when your mother’s ____ was fertilized by your father’s _____.
n Humans have one pair of chromosomes, called the ____ chromosomes.
n Sex chromosomes are represented as _____ and ____.
n Egg cells have only ___ chromosomes while sperm carry either an ___ or a ___ chromosome.
n At ______, _____ X chromosomes produce a ______(____).
n An X chromosome and a Y chromosome produce a ______(____).
n In most organisms, it is the ______that determines the sex of the offspring.
Sex-Linked Inheritance
n The Y chromosome is ______than the X chromosome.
n Several of the genes found on the X chromosome are not found on the Y chromosome.
n The genes on the X chromosome that have no matching genes on the Y chromosome are called ______.
n Sex-linked genes are usually ______.
n Two human ______associated with sex-linked genes are hemophilia (blood does not clot properly) and color blindness.
n Both of these disorders are more common in ______than in females.
¡ This is because the sex-linked recessive gene on the male’s X chromosome is the only gene the male has for the sex-linked trait.
n A female will not have hemophilia, color blindness or any other sex-lined condition, as long as she has ______normal gene for the trait.
¡ Females who have one recessive gene for a sex-linked trait are called “______” for that trait.
¡ That means they do not have the disorder, but they ______the recessive gene.
¡ Children of ______can inherit the sex-linked gene
Sex-Linked Inheritance
