Meiosis and reproduction Flashcards
How many sets of genes does a gamete have to have have?
One
The offspring of two parents obtain a single copy of every____ from each parent.
Gene
Where are genes located?
On chromosomes
What is a pair of corresponding chromosomes called?
Homozygous
The gametes of sexually reproducing organisms are?
Haploid or diploid
Haploid
During what stage does crossing over occur between tetrads?
Meiosis I or Meiosis II
Meiosis I
Specifically what phase of meiosis does crossing over occur in?
Prophase I
If a cell has 16 chromosomes when entering meiosis, how any will the daughter cells have?
8
During what stage of development do changes in gender begin to occur?
During the seventh week
Where does puberty start?
In your brain
What does the brain do to start puberty?
It tells the pituitary gland it to begin to produce follicle-stimulating hormone’s (FSH) and lutenizing hormones (LH).
Where are the male reproductive organs?
They are contained within the scrotum.
What is the purpose of the penis?
It delivers sperm to the female reproductive system.
What is the purpose of the Van Deferens?
It is the tube that carries mature sperm from the epididymis to the urethra.
What is the purpose of the urethra?
It is the tube that carries both the sperm and urine (not at the same time) out of the body.
What is the purpose of the seminal vesicle and the prostate gland?
It produces seminal fluid which nourishes and protects the sperm from the acidic female environment.
What is the purpose of the sperm?
They contain DNA and when paired with and egg the form a zygote.
What are the three parts of a sperm, and what do these parts do?
- Head – contains DNA, and enzymes that allow entry into the egg
- Midpiece – contains energy releasing mitochondria
- tail – provides locomotion
What is a sperm tail an example of?
Flagella
What is the purpose of the ovaries?
They are the female reproductive organs that produce eggs.
What is the purpose of the fallopian tubes?
They carry the egg to the uterus and fertilization occurs within them.
What is another name for the fallopian tubes?
The oviducts
What is the purpose of the uterus?
It is a hollow muscular organ that acts as the womb.
What is the purpose of the cervix?
Is the opening of the uterus and also steals it.
What is the purpose of the vagina?
It is the birth canal.
What is a zygote?
A fertilized egg.
What happens after a single sperm enters an egg?
A barrier is produced around the egg to keep others sperm out.
Where does fertilization occur?
In the fallopian tubes.
What does the zygote form as it goes through mitosis?
A ball of totipotent cells called the morula.
After about 4 days the zygote becomes a hollow ball of cells called the____.
blastocyst
6–7 days after fertilization the___attaches to the uterus wall. This is called___.
Blastocyst, implantation
In the blastocyst, the outer ring of cells will become the____ and the inter clump will become the____.
Placenta, embryo
What is an embryo?
A development stage that the zygote goes through in which cells become more specialized.
What is differentiation?
A process by which cells become more specialized.
When does differentiation occur?
After implantation.
What are totipotent cells?
Cells that can develop into any type of body cell and cells of the extra-embryonic.
What are pluripotent cells?
Cells that can develop into many types of cells but not every type.
Are the inner cells of an embryo pluripotent or totipotent?
Pluripotent
What are stem cells?
Unspecialized cells from which differentiated cells develop.
What are the two types of stem cells?
Embryonic stem cells and adult stem cells.
Are embryonic stem cells pluripotent or multipotent?
They are pluripotent.
Are adult stem cells pluripotent or multipotent?
They are multipotent.
What is the difference between adults stem cells and embryonic stem cells?
Embryonic stem cells have the ability to become any type of cell, while adults stem cells are more specialized and just replace old cells.
What are the benefits of stem cell research?
The cells could be used to repair or replace damaged cells.
What are the ethical issues with embryonic stem cell research.
With embryonic stem cell research there are many issues due to the fact that harvesting the cells destroys an embryo.
What are the two solutions to make stem cell research more ethical?
- New techniques that would allow cells to be removed without harming the embryo.
- reprogramming adults stem cells to become pluripotent.
What is gastrulation?
It is when cells differentiate into three germ layers.
What are the three germ layers created by gastrulation?
- endoderm- the lining of organs
- ectoderm- the skin and nervous system
- mesoderm- muscles, the skeletal system, and gonads
What is nuerulation?
The formation of the nervous system.
What is the first thing that is formed during nuerulation?
The neural tube, which will eventually become the brain and spinal cord.
What is the placenta?
An organ that connects the mother and the embryo.
What is the purpose of the umbilical cord?
It contains blood vessels that attach the embryo to the placenta.
What is the purpose of the amniotic sac (amnion)?
Is a membrane that surrounds the embryo and contains amniotic fluid.
After about eight weeks of development the embryo is called a ____?
Fetus
What happens during the first trimester?
- most of the major organs and tissues are already formed
- The baby moves and has reflexes
- The embryo become a fetus
When does the second trimester occur?
4–6 months into pregnancy.
What happens during the second trimester?
- tissue becomes more complex and specialized
- The heartbeat is detectable
- bone continues to replace cartilage
- hair is visible
- movement is felt by the mother
When does the third trimester occur?
7–9 months into pregnancy.
What happens during the third trimester?
- The organs mature
- The fetus grows in size and mass
- The lungs prepare for air
- The baby is able to regulate their own body temperature
- The CNS (central nervous system) fully develops
What are the organs were sperm is produced called?
The testis
What is a baby in the womb called?
A fetus
What are the contractions before childbirth triggered by?
A hormone called Oxytocin
What does the term after birth mean?
It is when the placenta and amniotic sac are released from the uterus.
What are the tiny tubes that sperm are made in called?
Seminiferous tubules
What stage of meiosis I or meiosis II does this occur in?
Each replicated chromosome pairs up with its corresponding homologous chromosome.
Prophase I
What stage of meiosis I or meiosis II does this occur in?
Crossing-over occurs between tetrads.
Prophase I
What stage of meiosis I or meiosis II does this occur in?
Paired homologous chromosomes line up across the center (equator) of the cell.
Metaphase I
What stage of meiosis I or meiosis II does this occur in?
Spindle fibers pull each pair of homologous chromosomes towards an opposite end of the cell.
Anaphase I
What stage of meiosis I or meiosis II does this occur in?
A nuclear membrane forms around each cluster of chromosomes, and cytokinesis follows forming 2 new cells.
Telophase I
What stage of meiosis I or meiosis II does this occur in?
Chromosomes consist of two chromatids, but they do not pair to form tetrads.
Prophase II
What stage of meiosis I or meiosis II does this occur in?
A nuclear membrane forms around each cluster of chromosomes, and cytokinesis follows forming 4 new cells.
Telophase II
