Mei/Mitosis Flashcards
What are the long threads of DNA inside the nucleus called?
Chromosomes
What is all of the material located inside the nucleus called?
Chromatin
How many chromosomes does a human have in a body cell?
46
What process do body cells use to reproduce?
Mitosis
What are the names of the phases of mitosis?
Prophase, Metaphase, Anaphase, Telophase
Where do spindle fibers originate from?
Centrioles
What phase does the cell do what it’s made for?
Interphase
During what phase does a cell replicate its DNA?
Interphase (S phase)
What are spindle fibers used for?
Guide wires for chromosomes
What are sister chromatids?
When DNA replicates the chromosome is now made up of 2 sister chromatids
Where are sister chromatids attached?
Centromere
During what phase does the nucleus dissolve?
Prophase
During what phase are the chromosomes at the middle of the cell?
Metaphase
During what phase does the nucleus reappear?
Telophase
During what phase do chromosomes move to opposite poles of t he cell?
Anaphase
What is a sex cell?
Sperm & Egg (haploid)
What are the phases of interphase & what happens in each phase?
G1 (Cell grows & does what it does); S (DNA is duplicated); G2 (Cell continues to grow & prepares for mitosis)
What is a somatic cell?
Body Cells (diploid): all cells except sex cells
What does malignant mean?
A tumor spreads
What does benign mean?
A tumor that doesn’t spread
What are things that cause cancer called?
Carcinogens
What does metastasize mean?
Spreading of cancer cells
What is a tumor?
A mass of abnormal cells that grow and divide uncontrollably
What does p53 protein do and what is the name of the gene that encodes for p53 protein called?
P53 protein checks DNA for mutations. The gene that encodes for the protein is the p53 gene.
What happens if the p53 gene is damaged in a cell and how can this lead to cancer?
There is no p53 protein, therefore it cannot check the DNA of the cell for mutations. If there is a mutation in a cell, it continues to divide when it sho uldn’t
How does a cancer cell differ from a normal cell ?
They can reproduce in isolation
they can move
they do not stick together
they don’t specialize
they serve no function
more dense chromatin
more nucleus & less cytoplasm
sometimes multiple nuclei or nucleoli
oddly shaped
Name 6 factors that can lead to cancer.
Age
Diet
Chemicals
Radiation
Electricity (DNA is negatively charged, so negative charge of electricity can effect DNA during DNA synthesis causing mutations)
Viruses (eg: cervica l cancer is caused by a virus)
Explain how somatic cell nuclear transfer works to clone animals.
A diploid somatic (body) cell is taken from an animal you want to clone and is brought close to an enucleated egg cell from another individual. Then zap with electricity causing the 2 cells to fuse. Now the 2N nucleus of the animal you want to clone is inside the dono r’s egg cell. The egg cell thinks it’s been fertilized and since it is now diploid begins to divide as normal. Take the developing embryo in pl ace it in the uterus of a surrogate mother. Wait until birth.
What are gametes?
Sex cells (egg & sperm)
What does diploid mean?
Full # of chromosomes (46 in humans)
What does haploid mean?
½ # of chromosomes (23 in humans)
What are homologous chromosomes?
They carry genes that control the same traits
List 3 things that homologous chromosomes have in common.
Size, shape, & gene arrangement
Why do we use sexual reproduction?
To diversify the gene pool (to create as many different individuals as possible in case of environmental change…some will be likely to survive)
Name each stage of meiosis.
Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II
What is synapsis and during what phase does it happen?
The process by which homologous chromosomes to create tetrads …homologous chromosomes line up)
What are tetrads and during what phase do they form?
They are made of 2 homologous chromosomes. They form during prophase I.
What is crossing over and during what phase does it happen?
The exchange of DNA…happens during synapsis during prophase
What is segregation and during what phase does it take place?
When homologous chromosomes go to opposite poles of the cell during anaphase I
When do sister chr omatids break apart?
During Anaphase II
What is the end result of meiosis?
4 different haploid cells
What is the formation of gametes called?
Gametogenesis
What is the formation of sperm called?
spermatogenesis
What is the process that makes egg cells called ?
oogenesis
What are spermatogonia?
They are the cells that undergo meiosis to produce sperm cells
What are oogonia?
They undergo meiosis to produce egg cells
What are polar bodies?
They are the cells that receive the small amount of cytoplasm wit h each cell division during oogenesis (they get absorbed by the body)
What are the differences between spermatogenesis & oogenesis?
Only 1 functional egg cell is formed, egg cells have a lot of cytoplasm, females are born with 400 000 egg cells, only 400 egg cells develop throughout life, meiosis is stalled during prophase I & finishes up once a month after puberty (only fully completes meiosis if fertilized)
What is a karyotype?
A picture of a person’s chromosomes lined up
What are the sex chromosomes an d which ones do males and females have?
The X chromosome and the Y chromosomes. Males have XY and females have XX
What is nondisjunction?
If homologous chromosomes do not separate properly during meiosis.
What is trisomy and give 1 example.
When an ind ividual ends up with an extra chromosome in all of their cells..Trisomy 21 (Down’s Syndrome)
What is monosomy and give 1 example.
When an individual ends up with 1 less chromosome in all of their cells.
Turner’ Syndrome
What sex chromosomes does a person with Klinefelter’s have?
XXY
What is gametogenesis?
The formation of gametes (sex cells)
How many sperm do men make per day?
1 billion
How many functional gametes are made during meiosis in spermatogenesis?
4
How many primary oocytes are females born with and what stage of meiosis are these cells frozen in?
Female is born with 400 000 primary oocytesm that are stuck in prophase I of meiosis
When does meiosis I complete in oogenesis?
Once a month after ovulation
What stage of meiosis does meiosis get stuck in as an oocyte makes its way down the fallopian tube?
Metaphase 2
How many functional gametes are made with one meiotic division?
1 for oogenesis
What are polar bodies and how many are made duri ng oogenesis?
Non-functional cells made during oogenesis. 3 are made
Explain oogenesis and the cells involved.
Females born with 400 000 eggs
Meiosis pauses in Prophase I
After puberty, once a month meiosis I finishes
As egg cell goes down fallopian tube, it freezes in Metaphase II
Only if an egg cell gets fertilized does it fully complete meiosis.
Only 1 functional gamete made, other 3 are called “Polar Bodies
What is nondisjunction and when can it happen?
When 2 homologous chromosomes do NOT separate during ANAPHASE I or ANAPHASE II
Some daughter cells end up with 1 more or 1 less chromosome than they should have
What is trisomy ?
Occurs when a person has 3 of the same chromosome, instead of just a pair
What is monosomy?
Monosomy – occurs when a person has only 1 member of a homologous pair
What are autosomes?
All of the chromosomes that are NOT sex chro mosomes
(Chromosome pairs #1 - #22)
What is a karyotype? (#2.)
A picture of a cell’s chromosomes lined up in homologous pairs
