Name: ______________________
Introduction to Genetics Webquest
Directions: Go to http://www.dnaftb.org/dnaftb/
Click on ENTER
We will be completing “Classical genetics” over two periods as well as for homework.
Concentrate on concept, animation, and problem in order to answer the questions.
1.
What is a trait?
An inheritable characteristic
What determines a trait?
Genes
What plant did Gregor Mendel study traits in?
Pea plants
What is cross-fertilization? Fertilization b/t two individuals of the same species
2.
How many traits did he study?
7
How many alternate forms is there of each trait?
2
What is a phenotype? The physical/observable result of your gene combo
What is an allele?
A version of a gene (Ex. Tall/Short for the height gene)
What is a genotype? combination of genes from your parents (Ex. Tt = tall)
3.
4.
How did Mendel discover that genes don’t blend?
Always resulted in yellow or green – never a blend/mix of the two
What would happen if you cross-fertilized a colored plant with a white plant?
If both were homozygous, it would always result in a colored plant (Yy)
What gene arrangement would the offspring have if a pure-bred green plant and a
pure-bred yellow plant were crossed?
YY (homozygous dom = yellow) X yy (homozygous rec = green) = Yy (yellow)
What is the difference between dominant and recessive?
Dominant is always expressed/shown
Recessive is usually hidden/carried
How are alleles related to genes?
Alleles are different versions of a single gene
What is the difference between homozygous and heterozygous?
Homozygous means 2 of the same alleles for a gene – Heterozygous is 2 different
alleles
5.
How many genes of each pair does a sperm and egg hold?
1 of each
Why is this important?
To give the offspring 2 of each after fertilization (one from sperm/one from
egg)
What is “mendel’s ratio”?
3:1
6.
7.
8.
9.
10.
What is the result of a heterozygous cross using a punnett square?
1:2:1 genotype ratio but a 3:1 phenotype ratio
What discovery pointed toward proving Mendel’s work?
The microscope could finally visualize DNA
Do all organisms have the same number of chromosomes?
NO
Where does life come from?
Pre-existing life
What process does the nucleus of a cell use to reproduce?
Mitosis
What process makes sex cells?
Meiosis
How many chromosomes does the sex cell of an organism have?
23
What process restores the normal chromosome number?
fertilization
What happens if two sperm fertilize an egg?
They will begin to divide, but unevenly and the fertilized egg will soon die
What is the female chromosome arrangement?
22 pairs of autosomes and 1 pair of sex chromosomes XX
What is the male chromosome arrangement?
22 pairs of autosomes and 1 pair of sex chromosomes XY
Which, male or female, determine the sex of an offspring?
Male – depends on if the zygote is created with a “Y” sperm or an “X” sperm
What are the odds that parents will have a boy or a girl?
50:50 or 1:1
What are the two types of fruit fly eye genes?
Red eyed “wild type” or white eyed “mutant”
Where is this gene located?
On the sex chromosomes – they are “sex-linked”
11.
What does it mean when genes are linked?
They are close to each other on the same chromosome an have a higher likelihood of
being inherited together. (red hair and freckles)
What process is “the entwining and exchange of genes”?
Crossing-over which creates genetic recombination
12.
What is the source of gene variation?
Random spontaneous mutation (with fertilization and meiosis)
What is “hybrid vigor”?
Refers to the “strength” of hybrids – individuals with genes from various sources
13.
List a few diseases of recessive inheritance?
Alkaptonuria and Albinism
What charts are used to track human inheritance?
Pedigree charts
What shape are the males – females?
Squares = male
Circles = females
What do horizontal lines mean – vertical lines?
Horizontal = married OR brothers/sisters
Vertical = descendants
(sons/daughters)
14.
Are behavior and health controlled only by genetics?
NO – The environment and upbringing play an equal role