Cell division quiz 1 Flashcards
Somatic Cells (Body Cells)
liver,
uterus, skin, nerve, testes, stomach, eye,
etc.
Gametes (Sex Cells)
egg & sperm
only.
Chromosomes:
DNA wrapped
around proteins
(histones).
DNA
= instructions
for protein
synthesis.
Chromatids:
identical
parts of a replicated
chromosome.
-Each contains an identical,
double helix of DNA.
Centromere:
attaches
“sister chromatids”
together.
Genes:
carry the code for making specific proteins!
- Gene
has a specific sequence (order) of
nucleotides that determines the:
* order of amino acids in a polypeptide/protein.
Alleles:
different versions of a
single gene.
Dominant allele:
codes
for a functional protein!
Recessive allele:
codes
for a non-functional
protein.
Homozygous:
2 of the same alleles.
Ex. AA (homozygous dominant)
aa (homozygous recessive)
Heterozygous (hybrid):
2 different alleles.
Ex. Aa
Allele Combinations:
Each person has 2 alleles for a single trait!
Homozygous Dominant:
Ex. AA 🡪 functional proteins supply the “dominant” physical trait.
Heterozygous:
Ex. Aa🡪 ~ 50% of the normal functioning protein = enough to
produce the “dominant trait.”
* Non-functioning proteins from the recessive allele are broken down &
have no effect.
Homologous Chromosomes:
Matching chromosomes
inherited from each
parent.
* Have the same genes
at the same locations,
but possibly different
alleles.
Homozygous Recessive:
Ex. aa🡪 physical trait observed is due to the lack of a functional
protein.
Haploid Cell:
a cell containing
one of each type
of chromosome.
Ex.
* Gametes: egg
& sperm
Diploid Cell:
a cell containing homologous
chromosomes (two of each type).
Ex.
* Somatic Cells
* Germ Cells or Primary Sex
Cells (give rise to egg & sperm)
* the Zygote (fertilized egg)
The Cell Cycle:
period of growth &
division of a cell
(timing differs/cell type.)
- Interphase(word def)
(G1, S, G2) – period between cell
divisions.logest phase of cell life
- Cell Division(word def)
(M Phase –
mitosis & cytokinesis.)
Interphase:
longest phase of the cell cycle (not part of mitosis.)
G1: Cell growth, organelle synthesis & SPECIFIC
life functions!
S: DNA Replication, histone synthesis.
(formation of “sister chromatids”)
G2: Centriole duplication, proteins form for
microtubule creation, final prep for division.
Cell Division:
One cell divides into 2
identical, smaller
daughter cells.
- Mitosis:
division of the
nuclear contents.
- Cytokinesis:
division of
the cytoplasm.
Asexual
Reproduction:
one parent
organism divides
into 2 identical
individuals of the
species.
Mitosis in Multi-celled Organisms used for:
*Growth
- Repair of damaged
tissues - Embryonic
development 🡪 🡪 🡪
Cell Division: 2 stages
(Mitosis & Cytokinesis)
Mitosis
consists of Prophase, Metaphase, Anaphase &
Telophase, & is followed by Cytokinesis.
Prophase:
Longest phase of mitosis.
* Chromatin condenses into
chromosomes (visible under compound light
microscope.)
* Nuclear membrane & nucleolus
disintegrate.
* Centrioles migrate to the poles.
* Spindle fibers form (microtubules that
help separate chromosomes!)
Metaphase:
*Spindle fibers attach to
sister chromatids @ the
centromere.
*Spindle fibers pull
chromosomes into a single
file line along the middle of
the cell.
Telophase:
*Chromosomes unwind
into chromatin. (NOT visible
under microscope.)
*Spindle fibers disintegrate.
* Nuclear membrane & nucleolus reform.
*Leads to cytokinesis…
Anaphase:
*Spindle fibers pull sister
chromatids AWAY from
each other to opposite
sides of the cell.
Animal Cell Cytokinesis:
- Cell membrane pinches
in as cleavage furrow
forms. - 2 smaller, identical,
diploid daughter cells
formed!
Plant Cell Cytokinesis:
*Cell plate forms during cytoplasmic division in order
to create a new cell wall.
Why does the timing of the Cell Cycle need
to be regulated?
Checkpoints in the cell cycle ensure that division
occurs when:
* There is sufficient growth & correct DNA replication.
At each checkpoint, many proteins participate in
precisely regulating each step of the cell cycle.
* Prevents uncontrolled cell division!
internal regulators
proteins that respond to events inside the cell
- they allow cell cycle to proceed only when certain process took place
apoptosis
programed cell death, so damaged cells don’t divide
cancer
uncontrolled growth and division
external regulators
speed up or slow down the cell cycle. grothfactors make sure that the cell is not getting to big
causes of cancer
Genetic mutations and environmental factors
tumor
mass of cells that have divided uncontrollably
cancer treatmets
chemo, radiation, surgery
