Studied by 4 people
Heredity / interhertiance
transmission of traits from one generation to another
What is genetics
the study of heredity and variation
*What are genes
Hereditary units of DNA (Units of inheritable traits)
What is the genome
All of the genes composed together
*** What is the point of meiosis
To make sperm and egg cells that might be used in sexual reproduction
What are gametes
Cells that are used by plants and animals to pass on their genetic info
What is the corresponding location for each gene called?
Locus
What are locus
The corresponding location at which each specific gene can be found
In asexual reproduction, what causes variation in family lines?
Mutations
What is karyotyping?
The matching up of pairs of chromosomes from longest to shortest.
What are the pairs of chromosomes used in karyotyping called?
Homologous chromosomes OR pairs of autosomes
(should know both probably!)
How many homologous pairs of chromosomes would a male have?
22 (Males have XY sex chromosome pair— NOT homologous)
How many homologous pairs of chromosomes would a female have?
23 (Females have XX sex chromosome pair— HOMOLOGOUS!! all 23 chromosomes are homologous)
Does the sperm or egg dictate gender of offspring?
SpermW
What are the two categories of chromosomes?
Autosomes and sex chromosomes
What are autosomes?
The chromosomes that are not the sex chromosomes :] easy enough
XY: male or female
male
XX: male or female
female
Is the sperm X or Y
Either X or Y
Is the egg X or Y
ALWAYS Y
*What does haploid mean
cells with a single set of chromosomes (not homologous pairs)
*What does diploid mean
Both sets of chromosomes; have to be homologous.
If a cell is haploid, you can immediately assume…
Meiosis is happening
What are the only haploid cells in the human body?
sperm and egg cells— GAMETES
When does the life cycle start?
when the egg meets the sperm and is fertilized
What process reduces the number of chromosome sets from diploid to haploid?
meiosis
How many cell divisions in meiosis? names?
2: meiosis I and meiosis II
How many daughter cells are produced in meiosis
4
what stage is the longest in meiosis?
Prophase I
What happens in prophase I? (6)
chromosomes condense
Homologous chromosomes form tetrads
Crossing over
centrosome movement towards poles
Spindle formation
nuclear envelope breakdown
How many chromosomes in 1 tetrad?
2
how many chromatids in 1 tetrad?
4
What is the point of crossing over?
to make unique gametes— genetic diveristyyy
How do you remember how many chromatids are in one tetrad??
Tertris = tetra = each piece in tetris is 4 blocks = tetra = four = tetrad
What are the only cells that do meiosis?
Germ line cells
Does meiosis make zygotes
no
What happens during metaphase I
tetrads align on the metaphase plate
What happens during anaphase I
sister chromatids move towards poles— REMAIN ATTACHED
what happens during telophase I and cytokinesis 1 (3)
each cell will have sister chromatids
cytokinesis
chromosomes might unwind (depends on organism)
In meiosis, what happens after telophase I and cytokinesis I?
Meiosis II!
What happens in Meiosis II?
The same thing as mitosis, except for crossing over. isn’t mitosis bc cells are haploid
*What makes meiosis unique? (5)
Synapses
crossing over
chiasmata
tetrads
Sisters stay attached
What 3 mechanisms contribute to genetic variation
independent assortment
crossing mover
random fertilization
**What is random assortment of chromosomes
The random orientation of the homologous pairs at metaphase I
*What formula is used to figure out how many possible combinations of assortments there are?
What does the variable represent?
2ⁿ
n = haploids
