Review 2 Flashcards
what is genome
the complete genetic material of an
organism (i.e. all DNA)
what is prokaryotic genome
single, double-stranded
DNA molecule in the form of a loop or circle.
what is eukaryotic genome
several double-stranded,
linear DNA molecules bound together with
proteins to form complexes called
chromosomes
* Each species of eukaryote has a different
number of chromosomes in the nuclei of its
cells
* E.g. human body cells (somatic cells) have 46
chromosomes (23 pairs)
what is diploid
when a cell contains two matched
sets of chromosomes
what is haploid
: when a cell has only one set of
chromosomes and is designated n
* Found in sex cells of eukaryotic organisms
* Gametes (sex cells) contain only one set of
chromosomes
* E.g. Human gametes (e.g. egg or sperm) contain
one set of 23 chromosomes
* Somatic cells in some organisms are haploid, but
this is rare (e.g. male bees, ants)
what is homologous chromosomes
the matched pairs of
chromosomes in a diploid organism
what is locus
the location at which specific nucleotide
segments are placed on a chromosome
what is gene
the functional unit of a chromosome,
which determines specific characteristics by
coding for specific proteins.
what is traits
the different forms of a characteristic.
* E.g. in humans: shape of earlobes is a
characteristic, free/attached are traits
* E.g. in humans, eye colour is a characteristic,
blue/green/brown/hazel/etc. are traits
what is the cell cycle
series of events involving cell
growth and cell division that produces two
new daughter cells.
what happens during interphase
the cell grows and DNA is
replicated (longest phase)
The cell undergoes normal processes while also
preparing for cell division.
* For a cell to go from interphase to the mitotic
phase, many internal and external conditions
must be met.
* Three stages of interphase: G1, S, and G2
The first stage of interphase
* Called G1 (or first gap) because little change is
visible.
* At biochemical level, cell is accumulating
building blocks of chromosomal DNA and
proteins, and enough energy reserves to
replicate each chromosome in the nucleus
What happens during Interphase: G1 phase
The first stage of interphase
* Called G1 (or first gap) because little change is
visible.
* At biochemical level, cell is accumulating
building blocks of chromosomal DNA and
proteins, and enough energy reserves to
replicate each chromosome in the nucleus
What happens during interphase: S phase
S phase (synthesis phase)
* DNA replication results in the formation of two
identical copies of each chromosome (called
sister chromatids) that are firmly attached by a
centromere
* Centromere is duplicated, which allows
mitotic spindle to develop
* these orchestrate the movement of
chromosomes in mitosis and helps organize
cell division
What happens during Interphase: G2 phase
- G2 phase (second gap phase)
- cell replenishes its energy stores and makes the
proteins necessary for chromosome
manipulation. - Cell may grow
- Some cell organelles are duplicated, and the
cytoskeleton is taken apart to form the mitotic
spindle
what happens during mitotic phase
he replicated DNA and
cytoplasmic contents are separated and the
cell divides
Divides the contents of the nucleus and
cytoplasm to make two identical daughter
cells
* A process in which duplicated chromosomes
are lined up, separated, and moved to
opposite ends of the cell, and then the cell is
divided into two new identical daughter cells.
what happens during synthesis phase
DNA replication results in the formation of two
identical copies of each chromosome (called
sister chromatids) that are firmly attached by a
centromere
- centromere is duplicated, which allows mitotic spindle to develop
G2 phase (second gap phase)
* cell replenishes its energy stores and makes the
proteins necessary for chromosome
manipulation.
* Cell may grow
* Some cell organelles are duplicated, and the
cytoskeleton is taken apart to form the mitotic
spindle
what happens during mitosis
the first part of the mitotic phase, which
accomplishes nuclear division
During mitosis, the cell nucleus divides
* Divided into 5 stages: prophase,
prometaphase, metaphase, anaphase, and
telophase
what happens during cytokinesis
second part of the mitotic phase,
which physically separates cytoplasmic
components into two daughter cells.
what happens during prophase
The chromosomes in the nucleus are made
more accessible
* nuclear envelope and ER break down
* Nucleolus disappears
* Centrosomes begin to move to opposite poles
of the cell
* sister chromatids coil more tightly and become
visible under a light microscope
what happens during prometaphase
Processes begun in prophase continue
* Chromosomes connect to cytoskeleton
* Nuclear envelope disappears
* mitotic spindle continues to get longer
* Chromosomes become more condensed and
can be visually distinguished
* Each sister chromatid attaches to spindle
microtubules at the centromere
what happens during metaphase
All of the chromosomes align in a plane
halfway between the two ends of the cell
* sister chromatids are still tightly attached to
each other.
* chromosomes are maximally condensed (i.e.
each is very distinct from others)
what happens during anaphase
sister chromatids are split apart at the
centromere
* Each chromosome is pulled to one side of the
cell by microtubules and centrosome
* cell becomes visibly elongated
what happens during telophase
Cell genetic components are packaged as two
individual daughter cells
* chromosomes reach the opposite ends of cell
and begin to decondense (unravel)
* mitotic spindles are broken down into
monomers that will be used to assemble
cytoskeleton parts for each daughter cell
* Nuclear envelopes form around chromosomes
what happens in cytokinesis
second part of the mitotic phase during which
cell division is completed by the physical
separation of the cytoplasmic components
into two daughter cells
* Stages of mitosis similar for most eukaryotes
* cytokinesis is different for eukaryotes with
cell walls (i.e. plant cells)
