D2.1 Cell Cycle Flashcards
State the name of the substance that stimulates meristem cells to proliferate and differentiate into specialised cells.
Auxin
_____ undergo budding
yeast
Why do cell division occur?
I. To produce gametes for sexual reproduction.
II. To allow a population of cells to grow while reducing their surface area-to-volume ratio.
III. To replace cells that have been lost or damaged.
I and III only
Describe cytokinesis in animal cells:
- Cleavage Furrow
- Contractile rings made of actin and myosin
- Pinches apart
Describe cytokinesis in plant cells:
-vesicles form in the center to create new membranes
-Microtubule scaffold
-Each new cell builds a new cell wall
The formation of a contractile ring during cytokinesis in animal cells and Muscle contraction involve:
actin and myosin
New cells are needed for ____, ______, and _________.
Growth
Repair
Reproduction
New cells come from _____ cells. This allows for ______ of life.
existing, continuity
Cytokinesis
division of the cytoplasm of a cell to form 2 daughter cells
Cytokinesis in animal cells:
- Cleavage furrow
- Contractile rings
- pinches apart
Cytokinesis in plant cells:
- Vesicles form in the center to create new membranes
- Microtubule scaffold
- Each new cell builds a new cell wall
Cell Type (mitosis/meiosis)
mitosis-Somatic/body cells
meiosis-Reproductive gametes
Ploidy (n) (mitosis/meiosis)
Mitosis - (2n) (46 chromosomes in a cell after division is complete)
Meiosis - (n) (23 chromosomes after cell division is complete)
of divisions and # of daughter cells (Mitosis/Meiosis)
Mitosis
- 1 division
- 2 daughter cells produced
Meiosis
- 2 divisions
- 4 daughter cells produced
Genetic variation? (mitosis/meiosis)
Mitosis: No (Body cells are identical)
Meiosis: Yes (Reproductive cells are unique)
Usually, a parent cell divides into __ daughter cells. Unequal division is possible with a _____, _____, ______.
2, nucleus, mitochondrion, any organelle that cannot be synthesized by the cell
Unequal division occurs in budding in _____. Asexual reproduction when ________. Bud receives a nucleus/some cytoplasm. New cell wall to separate. Small bud grows.
yeast, nucleus replicates/divides
Oogenesis: ________
Oogenesis produces: ____________
egg production; 1 viable oocyte and 3 polar bodies
Cells need to replicate ______ before division to _____________________.
nucleus, prevent formation of anucleate cells
Anucleate cells ____ synthesize _____. This inability makes them have _______. An example is __________.
can’t, proteins, limited lifespan, red blood cells (live only few months/ regenerate frequently)
Continuity-Mitosis
-2 genetically _____ daughter cells
-2n
-All cells have an identical and ________ copy of the ________.
-In asexual reproduction, the full genome is passed _______________.
identical, diploid, complete, genome, to the offspring
Meiosis-Change
-Gametes (4 cells)
-_____ (n)
-genetically unique (variation)
-Random assortment of genes
-half of _______
haploid, chromosomes
Prerequisite for Mitosis/Meiosis
—> Prior to cell division, DNA is elongated
—> DNA replicates and condenses into chromosomes
View diagram: before replication, after replication, after anaphase
Kinetochore acts as a _______ motor
Microtubule
Interphase (not a phase in Mitosis)
- DNA (in chromatin form)
- Growth (normal cell function)
- Synthesis (replication) of DNA
Prophase:
- Chromosomes condense
- Spindle microtubules assemble
- Break down of nuclear membrane
Metaphase:
- Middle line up of chromosomes
- Microtubules attach to centromeres
Anaphase:
- Cohesin loops are cut
- Tension from the spindle pulls sister chromatids apart
- Chromosomes move towards the pole
Telophase:
- 2 new nuclei
- New nuclear membranes form
- Chromosomes decondense back into chromatin
- Happens simultaneously with cytokinesis
Microscope Slides:
- use a root tip (lots of mitosis)
- Cuts and stain
- Squash under a slide
- Identify
Meiosis as a ________ division. ________ chromosomes
reduction
Anaphase I
separation of homologous chromosomes
Anaphase II
Separation of sister chromatids
Normal Meiosis results in 4 _____ _____ ___.
haploid, daughter, cells
Nondisjunction:
- Results in ______ with too many or ___ ____ chromosomes
- Usually results in ___ ______. Occurs in _____.
failure of the chromosomes to separate;
- gametes, too few, cell death, Meiosis 1 and Meiosis II.
Down syndrome is a result of
Trisomy 21
Diploid
-Diploid
-2n (pairs)
-somatic/body cells
-Produced by Mitosis/ or infertilization the fusion of 2 haploid cells
Haploid
-n (not in pairs)
-gametes
-Meiosis
Bivalent
a pair of homologous chromosomes
Synapsis
the fusion of chromosome pairs at the start of meiosis.
Chiasma
point of crossing over
Crossing over
exchange of alleles between nonsister chromatids of homologous chromosomes
of _____ and amount of genetic exchange seems to be ____
chiasma, random
Meiosis
Prophase 1 -crossing over
Metaphase 1 -homologous pairs align on the equator
Anaphase 1 -separation of homologous pairs
Telophase 1/Cytokinesis -ends with 2 haploid cells
Meiosis II
Metaphase II -chromosomes align in the center
Anaphase II -sister chromatids separate
Telophase II/Cytokinesis -ends with 4 haploid cells
Identify, between which of the following structures does crossing over occur.
Between non-identical sister chromatids in a homologous pair.
_______ control the cell cycle by activating cyclin-dependent kinases.
Cyclins
Identify which of the following groups of cells is likely to have the lowest mitotic index.
neurons in the brain (mitotic index measures cells that are actively dividing; there is low cell proliferation in the brain)
