lecture 17 Flashcards
What distinguishes living things from nonliving matter?
the ability of organisms to produce more of their own kind
What is the continuity of life based on?
the reproduction of cell, or cell division
What is cell division?
the reproduction of cells
What is cell theory?
cells come from other living cells
What are examples of prokaryotes?
bacteria and archaea
How do prokaryotes reproduce?
binary fusion (a type of cell divison)
What happens during binary fission?
-the chromosome replicates (beginning at the origin of replication) and the two daughter chromosomes actively move apart
-the plasma membrane pinches inward, dividing the cell into two
What type of cells undergo binary fission?
Prokaryotes and single-cell eukaryotes
Which came first; prokaryotes or eukaryotes?
prokaryotes
Where did mitosis probably evolve from?
binary fission
Binary fission is defined as ______ reproduction
asexual
Where does mitosis occur?
prokaryotes and single-celled eukaryotes
What does most cell division result in? What is the exception?
two daughter cells with identical genetic information
exception: meiosis for sperm and egg cells
What is a cells genome?
All the DNA in a cell
What do eukaryotic chromosomes consist of?
chromatin
What makes up chromosomes?
DNA and protein that condense during cell divisions
Where is chromatin found?
eukaryotic chromosomes
How many chromosomes does a somatic cell contain?
2 sets of chromosomes
What is a somatic cell?
a non-reproductive cells
What are gametes?
reproductive cells
What is an example of a gamete?
sperm and eggs
How many chromosomes do gametes have?
half as many chromosomes as a somatic cell (23)
True/False: every eukaryotic species has a characteristic number of chromosomes in each cell nucleus.
True
Do diploid cells have an even or uneven amount of chromosomes?
Even
What happens in preparation for cell division?
DNA is replicated and the chromosomes condense
What are sister chromatids?
joined copies of the original chromosomes
Cell division: Each duplicated chromosome has _______.
two sister chromatids
What is the centromere?
the narrow ‘waist’ of the duplicated chromosomes where the two chromatids are most closely attached.
Where are the two chromatids most closely attached?
the centromere
Cell division: what happens to the two sister chromatids of each duplicated chromosome?
they separate and move into two nuclei. they are now chromosomes
What process makes a chromatid a chromosome?
When the two sister chromatids separate and move into two nuclei
How many centromeres are there during cell divison?
one for each sister chromatid
Briefly explain the process of cell division?
-one chromosome duplicates (including DNA replication) into two sister chromatids connected by their entire length (chromatid cohesion)
-each chromatid contains a copy of the DNA molecule
-the sister chromatids separate into two chromosomes and distribute them into two daughter cells
Cell cycle: what phases does the cell cycle consist of?
mitotic (M) phase ( mitosis and cytokinesis)
interphase (cell growth and copying of chromosomes for divison)
Cell cycle: What phase makes up 90% of the cell cycle?
interphase
Cell cycle: what are the 3 phases of interphase and describe them?
G1 phase “first gap”
S phase “synthesis”
G2 phase “second gap”
Cell cycle: What phase are chromosomes duplicated in?
S phase
Cell cycle: What phase do cells grow in?
All the phases: G1, S, and G2
Cell cycle: What are the stages of mitosis?
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
How many stages of mitosis are there?
5
Cell cycle: How are the stages in mitosis distinguished?
-Changes in status of nuclear envelope
- Degree of chromosomes condensation (Nucleoli)
-Sister chromatid cohesion
-Status of mitotic spindle
-Position of centrosomes
Cell cycle: What is the mitotic spindle?
made up of microtubules that control chromosome movement during mitosis
Cell cycle: Where does the assembly of the mitotic spindle being in animal cells?
the centrosome, the microtubule- organizing center (MTOC)
Cell cycle: When does the centrosome replicate?
during interphase
Cell cycle: What happens to the centrosome in prophase and prometaphase?
they migrate to opposite ends of the cell
Cell cycle: When does the centrosome migrate to opposite ends of the cell?
prophase and prometaphase
Cell cycle: What is on each end of each centrosome?
and aster
Cell cycle: What is an aster?
a radial array of short microtubules that extends from each centrosome
Cell cycle: What does the spindle include?
centrosomes, spindle microtubules, and asters
True/False: A cell can still divide if the centrosome is removed?
True
Cell cycle: Where does a lot of error occur?
mitosis
Plant cells do not have ____ or ____ and are still capable of cell divison.
centrioles and centrosomes
What is thought to have evolved as an improvement to cell division?
centrioles
Cell cycle: what happens during prometaphase?
the nuclear envelope breaks down and spindle microtubules begin to attach to the kinetochores of chromosomes and begin to move the chromosomes
Cell cycle: What are kinetochores?
protein complexes associated with centromere
Cell cycle: what are the protein complexes associated with centromere?
kinetochore
Cell cycle: What happens to the chromosomes during metaphase?
the chromosomes are all lined up at the metaphase plate
Cell cycle: What is the metaphase plate?
an imaginary plane midway between the spindles two poles
Cell cycle: What happens during the beginning of anaphase?
the sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell
Cell cycle: What happens at the end of anaphase?
duplicate groups of chromosomes have arrived at opposite ends of the elongated cell
Cell cycle: When does cytokinesis begin and what happens?
during anaphase or telophase, the spindle eventually disassembles
Cell cycle: What happens during the cytokinesis of animal cells?
-The cleavage furrow forms near the old metaphase plate
- a contractile ring of actin microfilaments associated with myosin motor proteins forms on the cytoplasmic side
Cell cycle: What happens during cytokinesis in the plant cell?
-they don’t have a cleavage furrow
- vesicles derived from the Golgi move along microtubules to produce a cell plate int he middle of the cell, vesicles carry cell wall material
- it continues to fuse with plasma membrane, new cell wall forms between daughter cells
Cell cycle: is there a nuclear envelope in G2?
Yes it is fully in tact?
Cell cycle: Is there a nuclear envelope in prophase?
Yes
Cell cycle: Is there a nuclear envelope in prometaphase?
No only fragments
