Chapter 10 Flashcards
what is a blastula?
a very early organism
in terms of mitosis, how do prokaryotes and eukaryotes differ?
prokaryotes have no membrane-bound organelles, so no nucleus, and their DNA is in the cytoplasm so mitosis is easier than eukaryotes, who have to remove the nuclear membrane before division
list the 4 reasons why cells divide?
- to replace existing cells
- growth and development
- repair
- reproduction
how long do skin cells usually last before they are replaced by mitosis?
about 10 days
what is a zygote?
the union of sperm and egg nuclei
what is binary fission?
prokaryotic cell division
list the 5 steps of binary fission
- copy circular chromosomes
- 2 circular chromosomes in the nucleoid region
- cleavage furrow forms (like play dough)
- formation of the septum that divides the cell
- 2 separate cells, identical to each other`
what is inside the nucleoid region of bacteria?
a single, circular chromosome of DNA and associated proteins
what phase of the cell cycle does the cell spend most of its life in?
interphase
how much of a portion of a cell’s life is mitosis?
very little
what is cytokinesis?
the physical separation of 2 daughter cells
what are the 3 phases of interphase?
- G1
- DNA synthesis
- G2
what happens in G1 of interphase?
cellular growth and maintenance
what happens is the DNA synthesis, or S phase of interphase?
DNA replication
how long is the S phase of interphase?
very short
what is/what happens in G2 of interphase?
short growth phase, prep for division
list the 5 steps of the eukaryotic cell cycle
- G1
- S
- G2
- Mitosis
- Cytokinesis
1-3 are interphase
since DNA is a large molecule, what is it partitioned into?
chromosomes!
what are chromosomes?
specific sequences of DNA, can be 10,000-200,000 nucleotides in length
what are genes? give an example
specific nucleotide sequences for a specific protein
ex. phosphofructokinase
what is chromatin?
loosely organized chromosomes, proteins, and RNA
what form is DNA in during G1 of interphase?
loosely organized chromatin that is hard to replicate and divide evenly
when do chromosomes begin to organize for more even replication and division?
late G1, just before S phase
what is a karyotype?
a picture of all homologous chromosome pairs of an individual
what does each member of a homologous pair do?
a specific trait
what is a homologue?
A chromosome that is similar in physical attributes and genetic information to another chromosome with which it pairs during meiosis
do members of a homologous pair have to be the same length?
no
where do members of homologous pairs come from?
parents; 1 maternal, 1 paternal
what genetically causes down syndrome?
3 chromosomes of pair #15 instead of just 2
what are sister chromatids?
each side of a replicated chromosome during S phase
what are the 3 parts of interphase?
- G1
- S phase
- G2
what is G1 of interphase?
primary growth/normal cell action, signals S phase
what is the S phase of interphase?
DNA replication/synthesis
what is G2 of interphase?
the final growth phase before mitosis
list 3 things that attach sister chromatids to each other
- cohesin proteins, in the middle
- microtubules, for movement
- kinetochores, also for movement
list the FIVE phases of mitosis
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
what 5 things happen in prophase?
- chromosomes condense and become visible
- chromosomes appear as 2 sister chromatids, held together at the CENTROMERE
- cytoskeleton is disassembled; spindle begins to form
- golgi and ER are dispersed
- nuclear envelope breaks down
what is prophase?
the prep phase!
what 3 things happen in prometaphase?
- chromosomes attach to microtubules at the kinetochores
- chromosomes positioned with kinetochores of sister chromatids attached to microtubules from opposite poles
- chromosomes move to equator of the cell
what has happened to the nuclear membrane by prometaphase?
complete breakdown
what is prometaphase, put simply?
attachment phase
what 2 things happen in metaphase?
- all chromosomes are aligned at equator of the cell (metaphase plate)
- chromosomes are attached to opposite poles and are UNDER TENSION
what is metaphase, simply?
in the middle phase
what is the equator of the cell also called?
metaphase plate
what 3 things happen in anaphase?
- the proteins holding the centromeres of sister chromatids are degraded, freeing individual chromosomes
- chromosomes are pulled to opposite poles (Anaphase A)
- spindle poles move apart (Anaphase B)
what happens in anaphase A?
chromosomes are pulled to opposite poles
what happens in anaphase B?
spindle poles move apart
what is anaphase simply?
moving/pulling phase
what 4 things happen in telophase?
- chromosomes are clustered at opposite poles and decondense back to chromatin
- nuclear envelopes reform around chromosomes
- golgi complex and ER reform
- cell begins to pinch off
what is telophase simply?
getting back to normal phase
what is cytokinesis?
pinching the mitosisified cell in half to make 2 new daughter cells
what is the difficulty level of cytokinesis in animal cells and why?
easy, there is only the plasma membrane
what is the difficulty level of cytokinesis in plant cells and why?
hard, a new cell wall must form before division
what is cytokinesis like for fungi and some protists?
more steps than animal cells
what is the pinching in of animal cells during cytokinesis called?
cleavage furrow
how does cytokinesis work for plant cells that need to build a new cell wall before dividing?
vesicles with cellulose move to the middle and knit together to form the new cell wall
what 3 checkpoints control the cell cycle?
- G1/S checkpoint
- G2/Mitosis checkpoint
- late metaphase (spindle) checkpoint
what is the G1/S checkpoint?
in interphase, controlled by ligands
what does the G2/Mitosis checkpoint check for?
all materials for mitosis? if so, proceed :)
what does the late metaphase (spindle) checkpoint check for?
make sure chromatids are aligned before yanking them apart
what happens if the cell is not prepared at a checkpoint?
the cell hits pause until everything is ready
why are there checkpoints to control the cell cycle?
the cell doesn’t want to waste energy and resources if it’s not ready to divide
what is a result of failure to control the cell cycle?
cancer
what are the 2 kinds of genes that can disturb the cell cycle when they are mutated?
- tumor-suppressor genes (good)
2. proto-oncogenes (bad)
what do tumor suppressor genes do?
activate cell cycle control
what do proto-oncogenes do?
promote genetically based cancer
what are the nongenetic factors that cause cancer?
mutagens
what are mutagens?
chemicals, outside damage; like radiation (sun, x rays), sterilization gas for medical equipment, PCB’s
how does DNA play a role in cancer?
if the DNA is damaged, it will tell cells to keep on dividing instead of stopping mitosis when need be
what are the 2 types of cancer?
benign and malignant
compare and contrast benign and malignant cancer
be ready for this to be an essay question
they are both tumor forming and use neovascularization, but benign tumors are encapsulated and self-contained in a membrane, and don’t spread to other tissues so they are not invasive, whereas malignant tumors are very invasive and spread far beyond the tumor site
what is neovascularization?
forming new blood vessels to feed the tumor, malignant tumors use this to upregulate the body’s metabolism to favor growth of the tumor over growth of the body
give an example of a benign tumor
fluffly the poodle’s 3 lb leg tumor
give an example of a malignant tumor
Dr. RC’s husband’s squamous cell carcinoma
