Meiosis & Introduction to Genetics Notes
Why do we look the way we look?
Our ___________________ controls how we look.
Where does our DNA come from?
If you and your siblings all have your parent’s DNA, why do you look so different?
Our mom’s cells have a full set of ___________________________.
Our dad’s cells have a full set of ____________________________.
If mitosis happened in the cell with the DNA we got from our parents, would it work???
MITOSIS REVIEW!
One cell duplicates all of its DNA and organelles to become __________________________.
Are the daughter cells identical to each other? _________
How are they identical to each other? _____________________________
Meiosis is the cell division process when a cell with a ____________ of chromosomes (__________) divides to
form a ____________ with _________________________________________.

Starts with ________________ and ends up with __________________!
Body Cells
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Most cells in our bodies have a _______________ set of chromosomes.
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Cells with a full set of chromosomes are called __________________________.
In humans diploid cells have ____________________________. (___________ pairs)
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We get _____________________________ from mom’s egg.
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We get ____________________________ from dad’s sperm.
How many chromosomes are in a blood cell???
How many chromosomes are in a skin cell???
Homologous Pairs
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Each set of 2 chromosomes is called a ____________________________________
Within a homologous pair…
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1 homologue is from the ____________________
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1 homologue is from the ____________________
Homologous chromosomes each contain genes that affect the ______________________.
If a species had 2 pairs of homologous chromosomes, how many chromosomes would that species have?
Sex Cells
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Some cells in our body have __________ of a set of chromosomes.
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Cells with ½ of a set of chromosomes are called _______________________
Sex cells are also called ____________________.
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Male sex cell =
-
Female sex cell =
If a human body cell contains 46 chromosomes, how many chromosomes do human sex cells contain?
Where does meiosis take place?
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Unlike mitosis, meiosis ONLY in specialized parts of the body called ____________________________.
o Remember, meiosis makes ____________________!!!!
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Males =
-
Females =
Meiosis has 2 parts
1. __________________________
2. __________________________
Meiosis I
Prophase I
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Identical chromatids ________________ together.
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Chromatids pair with _____________________________
Metaphase I
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Tetrads line up in the ____________________
Anaphase I
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Homologous pairs ____________________
Telophase I
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Each cell has identical chromatids still __________________
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Cytokinesis – ___________________________________
Meiosis II
Prophase II
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Nucleus membrane ____________________ and spindles ________________
Metaphase II
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Chromosomes line up in the ________________________________
Anaphase II
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Chromatids are _______________________
Telophase II
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______ cells are produced
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The cells are ____________________ cells
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Each cell is ______________________ different
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These cells are ____________________________ (___________________ and __________________)
If you and your siblings all have your parent’s DNA, why do you look so different???
Meiosis produces __________________________________ from __________________________.
Are these daughter cell identical???
Meiosis creates variation in ________ different ways:
1. ___________________________________________________
2. ___________________________________________________
Independent Assortment
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After homologues pair up, they line up in the ________________________________ and
________________________________.
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The homologue that lines up on the left goes to the _____________________________________
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The homologue that lines up on the right goes to the ____________________________________
Crossing Over
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Crossing over is the ____________________________________________________________________
____________________________________________________________________________________
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When pairs of homologues line up during ______________, the _______________________________
_______________________________________
Without crossing over…
With crossing over…
Asexual Reproduction
1. Cells divide by __________________
2. Crates ___________________________________________________
3. Works best for a ____________________________________________
4. Helps a population __________________________________________
Examples –
Sexual Reproduction
1. Cells divide by __________________
2. Crates __________________________
a. ________________________________________
b. ________________________________________
3. Genetic variation is good in a ____________________________________________
4. Requires ___________________________________________ and is _______________________ than
asexual reproduction.
Characteristics
Type of cell occurs in
# of nuclear divisions
# of daughter cells produced
Haploid or diploid daughter cells
Daughter cells genetic makeup is
the same or different from parent
cell
Mitosis
Meiosis
Introduction to Genetics
We already know that if you look carefully at all 46 chromosomes, you would see that there are _____ of
each type or 23 pairs (1 of each pair comes from _________ and the other is from _______).
This means that there are actually two chromosomes with instructions for each kind of trait (such as freckles,
nose shape, etc.)
_________________ are segments of DNA or the places on the chromosome that code for specific traits such
as height, eye color, etc.)

Each chromosome is made up of hundreds to thousands of genes that we inherit from our parents!
Genotype: ________________________________________ of a trait
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Example:
Phenotype: _______________________ appearance of a trait
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Example:
Allele: alternate form of a ____________________
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For eye color, what alleles could you have?
Dominant:
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Represented by __________________ letter
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Masks (_________________________________________) a recessive allele
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Example:
Recessive:
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Represented by __________________________ letter
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Is masked (____________________________________________) a dominant allele
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Example:
Homozygous: _________________________________ having the ____________________ two alleles
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“homo” = __________________
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“zygote” = _________________
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AA or aa
Heterozygous: ________________________________ having two ________________________ alleles
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“hetero” = ________________
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“zygote” = _______________
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Aa
What would be the genotype it: T = tall and t = short
Homozygous tall __________________
Heterozygous tall _________________
Homozygous short ________________
Can there ever be a heterozygous short???
Punnett square: toll used to predict _______________________ and ________________________ of
offspring.
EXAMPLE OF MONOHYBRID!!!!!!!
T = tall
t = short
Mom = Tt
Dad = Tt
Will their children be tall or short?
To find out we have to _____________________!!!
Tt
x
Mom x
Tt
Dad
Steps to using punnett squares:
1. Draw box
2. Put one parent’s gametes on top and the other along the left side.
3. Fill in the box with a letter from each parent.
4. Analyze!
Phenotype Ratio:
__________________________________________
Genotype Ratio:
__________________________________________
When we just cross one trait, it is called a _________________________________________________
When we do a genetic problem where we cross 2 different traits, it is called a
________________________________________.
Independent Assortment – when gametes are formed, genes move into these gametes _______________ of
other genes. This occurs only if these genes are on ____________________________ chromosomes.