The Cell Cycle Flashcards
what is cell division
-ability of organisms to reproduce
-continuity of lifeis based on the reproduction of cells (passing on genetic info)
roles of cell division
reproduction
growth and development
tissue renewal and repair
what is a chromatin
dna when the cell is not dividing (present in long thin threads)
what is a chromosome
dna during cell division (chromatin tightly coils around histones)
what characteristics are controlled by genes
hair
skin
flower color
where are genes located
on the chromosomes
what are genomes
all the genetic material in a cell
what does each chromosome contain
huge molecule of dna and proteins
contains a larger number of genes
what is the gene locus
the specific place on a chromosome where a gene is located
where does each gene occur
occurs on a specific chromosome at a specific site on the chromosome
how many are in a human
46 (23 from mom and 23 from dad)
true or false: number of chromosomes doesn’t mean how advanced the species is
true
what is a karyotype
organized profile of a person’s chromosomes
how is a karyotype arranged
stained
arranged by size (largest to smallest)
photographed
what are the 23 pairs of chromosomes
22 autosomes (non sex)
1 sex chromosomes
what are karyotypes used for
to check irregularities in the number or structure of chromosomes
why do you need an x sex chromosome
it has important genes for blood clotting and eyesight
it is sex defining
what does karyotype arrangement do
helps scientists quickly identify chromosomal alterations that may result in gentic disorders
what does having an extra chromosome lead to
Down syndrome (trisomy 21)
what is a haploid cell and examples
cell that has 23 chromosomes
–egg and sperm
–N
what are diploid cells and examples
23 pairs of chromosomes
–all somatic cells
–2N
what are non reproductive chromosomes called
autosomal or autosomes
what do autosomes do
-they don’t code for sex characteristics (m/f)
-found in somatic cells and gametes (but in diff quantities)
what is a somatic cell
cell that isn’t gametic
what happens when the sperm and egg cell unite
the nuclei fuse together to form a single nucleus = zygote
what is a zygote
a fertilized egg
when does the cell cycle happen
between the time a cell is formed and when it divides into two daughter cells
what is the cell cycle
describes the series of events that occur in nearly every cell
what is the process that follows after a zygote is formed
-initial cell divides into 2 then those 2 into 4 then those for into 8…
-basically the og genetic info is copied (cloning)
what are the characteristics of mitosis
-results in 2 identical body cells
-occurs during growth and repair
in somatic cell division
what is the purpose of meiosis
gives rise to gametes that hav half the number of chromosomes as the og cell
what are the stages in the cell cycle
-growth of the cell following cell division
-copying gentic info
-distribution of copies to daughter cells
*highly regulated and shortest stage is actual cell division
what are the names of stages in the cell cycle
-interphase (G1, S, G2)
-mitotic phase (mitosis, cytokinesis)
how long does interphase happen compared to the mitotic phase
interphase is most of the cells lifespan (95%)
what are the phases of interphase
G1: growth 1
S: dna synthesis
G2: growth 2
characteristics of growth 1
-begins as soon as daughter is formed
-period of active growth (increases in size until it reaches mature size for cell type)
-synthesis of new organelles
-dna is in chromatin form
-non-dividing cells are in this state
what happens during dna synthesis
-the chromatins are copied
-chromosomes are not condensed in this phase
what are the copied chromatins referred to as
sister chromatids (still considered one chromosome cause attatched to each other)
what are the characteristics of the sister chromatids
-contain the same genetic information
-attached at the centre with a centromere
how many chromatids are there during and after dna replication
- after = 92 (46 double sister chromatids)
-during dna replication = 46 sister chromatids
what happens in the the 2nd growth phase of interphase
-final stage (occurs after S phase of interphase)
-cell increases slightly
-begins preperation for the miotic phase of the cycle
-spindle fibers form (microtubules)
-chromosomes are not condensed
what happens by the end of interphase
-chromosomes have been copied
-centrosomes duplicated
-spindles have formed
what are the steps of mitosis
prophase (early)
prometaphase (late)
metaphase
anaphase
telohase
what are the two parts of the mitotic phase
mitosis
cytokinesis
what happens in prophase
-dna condenses (still called sister chromatids)
-nuclear envelope breaks
-centrosomes separate and move to opposing sides
-microtubules fibers extend between the centrosomes to form the mitotic spindle (some attach to chromosomes)
why are chromosomes condensed
easier for transportation in body, prevents dna breakage
what happens during prometaphase
-nuclear membrane is broken down
-centrosomes are at opposing sides
-some microtubules attach to centromere region
-nucleoli disappears
what is the centromere region called
kinetochores
what happens in metaphase
chromosomes align in the middle of the cell (single file)
what happens in anaphase
-centromeres breaks and the sister chromatids separate (now called chromosomes)
-chromosomes are pulled to opposite ends of the cell
cell elongates
what are chromatids that are no longer attached to their duplicates called
chromosomes
what happens during telophase
-spindle fibers disappear
-nuclear membrane forms around the chromosomes
-nucleolus reappears
-chromosomes unwind and become less compact
what marks the end of mitosis
telophase
what is cytokinesis
separation of cells and cytoplasm
what happens during cytokinesis
cell pinches along the middle and ends with two identical daughter cells
how is mitosis different in plant cells
-they don’t have centrioles but they have microtubule organizing centers
-cell can’t pinch in half
how do the new cells separate in plant cell mitosis
separated by cell plate
what are the steps in cytokinesis in plant cells
-vesicles from the golgi carry cell wall components to the middle
-cell plate forms at the center and becomes a cell membrane
how do prokaryotic cells divide
binary fission (asexual cloning)
most bacteria have how many chromosomes
one
how does binary fission work
-chromosomes replicate
-move to opposite sides
cell elongates to make room
plasma membrane grows inwards
-split
what happens if the cell doesn’t pass a checkpoint
-the cell tries to correct it
-if it can’t it undergoes apoptosis (cell suicide)
-program of cell death
what are the checkpoints during mitosis
G1 checkpoint
G2 checkpoint (between G2 and M)
M checkpoint (between metaphase and anaphase)
what’s does the G1 checkpoint check
growth factor proteins
nutrients
cell size
dna damage
what does the G2 checkpoint check
cell size
dna damage
dna replication
what does the M checkpoint check
chromosome attachment to spindle
what is the purpose of the checkpoints
cancer prevention and mutation prevention
-not a good idea to make a copy of a damaged cell
what is cancer
disease of the cell
excessive cell growth and division that is not controlled
mutagens can be caused by
-various agent that changes the dna of an organism (radiation, light, chemicals)
-increases frequency of mutation
what is a mutagen
anything that can bring about a mutation in DNA
what are benign tumours
-mass of cells that don’t invade neighbouring tissue
-not considered cancer
-can be removed
-can grow large
what are malignant tumours
-mass of cells that invade neighbouring tissues
-can impair functioning of one or more organs
-considered cancerous
-can spread to the whole body
what is it called when a cancer spreads to parts away from original site
metastasis
how does metastasis work
cancer cells get into the bloodstream and move throughout the body
what are the treatments for cancer
surgery
high energy radiation
chemotherapy
what is the process of high energy radiation and what is it used for
non specific damage to the dna because cancer cells have lost their ability to repair dna
used for localized tumors
what is chemotherapy used to treat and how does it work
used for metastatic tumors
damage actively dividing cells
taxol freezes the mitotic spindles by preventing microtubule formation
side effects of chemo
nausea immune suppression hair loss
why doesn’t your immune system attack cancer cells
because it’s your own cells so the immune response doesn’t recognize them as dangerous
