Chapters 11.4, 34.3, 34.4, and 10.4 Flashcards
What is produced by meiosis?
4 haploid cells total
Describe how crossing over increases genetic diversity.
Chromosomes exchange DNA. This creates more unique chromosomes and more genetic diversity.
What happens during metaphase 1 and how is genetic diversity increased?
Spindle fibers move tetrads to the cell equator randomly which increases genetic diversity.
What is the end product after cytokinesis 1?
2 haploid cells
What determines when cytokinesis 1 begins?
The formation of the cleavage furrow
What are the two different cell types?
Somatic and sex cells
Meiosis creates more ______ and ______, while mitosis creates more
egg & sperm, body cells
What is meiosis?
A process in which our gametes (sperm & egg) reproduce
What else is meiosis called? Why?
Reduction division because the number of chromosomes is being cut in half.
What does meiosis 1 alone create?
2 haploid cells
What does interphase 1 start with?
A diploid cell (set of chromosomes from each parent)
What are the three stages of interphase and what happens in each?
G1 period of growth, S DNA replication, G2 organelles copied and preparation for division.
What all happens in prophase 1?
Centrioles begin to create spindle fibers and move to opposite poles, nuclear membrane and nucleolus break down, chromatin coils into chromosomes
What are homologous pairs?
Chromosomes that are the same size, shape, or genetic material
What’s a synapsis and what does it form?
A synapsis is when homologous chroomosomes pair up, forms a tetrad.
What is a tetrad?
4 sister chromosomes
What is crossing over and what does it do?
When homologous chromosomes wrap around each other. It also increases genetic diversity by creating unique chromosomes.
Crossing over is completely _______.
random. ex: yeet, 21
How can you tell the difference between metaphase in mitosis and meiosis?
in mitosis there is one row of chromosomes, in meiosis there are two rows of chromosomes
What happens in anaphase 1 and what is left on both sides after?
pulls the tetrads apart to both sides, one chromosome is left on each side after
What happens in telaphase 1 and what marks the end of it?
Nucleolus and nuclear membrane reform, spindle fibers break apart. Cleavage furrow marks the end of this stage.
What marks the beginning of cytokinesis and what happens in this stage?
Formation of the cleavage furrow. It is the division of the cytoplasm.
What is created after cytokinesis?
2 haploid sex cells
List two major differences between meiosis 1 and 2.
Meiosis 2 normally skips interphase 2 and goes straight to prophase 2, and DNA isn’t copied in meiosis 2
What is meiosis 2 very similar to?
Mitosis
What happens in prophase 2?
Centrioles form spindle fibers, nucleolus and nuclear membrane break down, chromatin coils to form chromosomes.
What happens in metaphase 2?
Spindle fibers move chromosomes to the middle
What happens in anaphase 2?
Spindle fibers pull sister chromatids apart, leaving one chromatid on each side.
What happens in telophase 2 and marks the end of it?
Nucleolus and nuclear membrane break down, spindle fibers break apart. cleavage furrow formation marks the end of this phase.
What marks the beginning of cytokinesis 2?
Cleavage Furrow
What is the end product of cytokinesis 2?
4 haploid gametes with 23 chromosomes
Describe the process for males.
Spermatogenesis; 4 spermatids form
Describe the process for females.
Oogenesis: 1 egg and 3 polar bodies formed, eggs get all of the cytoplasm, and the other 3 polar bodies break down.
How often do females make eggs?
Every 28 days (periods)
Female eggs pause in ____ until a female reaches ___.
Meiosis 1, puberty
What are the four major differences between meiosis and mitosis?
Mitosis: - one cell division - starts and ends with a diploid cell - 2 identical daughter cells form - no tetrad, synapsis, or crossing over Meiosis: - two cell divisions - starts with a diploid cell and ends with haploid cells - 4 genetically diverse offspring form - have tetrads but only in meiosis 1
How do we all start?
We all start the same as a diploid zygote.
What happens around the 7th week of development?
Things begin to change on a cellular level. The gender becomes more noticeable.
What is formed when a sperm fertilizes an egg?
Diploid zygote
What are boy and girl gonads?
testes for boys, ovaries for girls.
What are boy and girl sex hormones?
Testosterone for boys, estrogen for girls.
What are sex hormones?
At certain points of a month the estrogen levels increase to be ready for a pregnancy
During childhood, what produces sex hormones?
gonads and adrenal glands in low levels
Where are the adrenal glands in the body?
Right above each kidney
Do opposite sexes produce small amounts of the opposite sexes hormone?
yes
What happens technically during menstrual cycle?
At certain points of a month the estrogen levels increase to be ready for pregnancy
When do menstrual cycles stop for a while and what happens to her levels during this?
Pregnancy, rise
Why do they monitor estrogen levels in pregnant women?
Because if levels become too low or high there is a risk of having a miscarriage
What happens when your levels are low?
They give you hormone injections to protect from miscarriages
What happens during menopause?
Women stop producing hormones and stop having periods and are no longer able to become pregnant