Chapter 2: Mitosis and Meiosis Flashcards
Are segments of the DNA that code for specific proteins which direct the metabolic activities of cells.
Genes
Is organized into chromosomes which serve as vehicles for transmitting genetic information.
DNA
Characteristically defined by the presence of a nucleus and other membranous organelles.
Eukaryotic cell
A membrane-bound structure that houses the genetic material, DNA, which is complexed with an array of acidic and basic proteins into thin fibers.
Nucleus
Present inside the nucleus which is an amorphous component where ribosomal RNA (rRNA) is synthesized and where the initial stages of ribosomal RNA (rRNA) assembly occur
Nucleolus
Portions of the DNA that encode rRNA.
Nucleolus Organizer Region (NOR)
Lacks a nuclear envelope and membranous organelles.
Prokaryotic cell
The genetic material of prokaryotic organisms.
Circular DNA
A region in the cytoplasm of prokaryotic organisms where the genetic material is clustered into.
Nucleoid region
True or False. The genetic material in prokaryotic organisms undergoes the extensive coiling characteristic of the stages of mitosis, during which the chromosomes of eukaryotes become visible.
False. Genetic material in prokaryotes does not undergo coiling.
True or False. Prokaryotic cells do not have a distinct nucleolus and do not contain genes that specify rRNA molecules.
False. Though deprived of a nucleolus, prokaryotic cells do contain genes that code for rRNA.
The remainder of the eukaryotic cell within the plasma membrane, excluding the the nucleus.
Cytoplasm
Compartmentalizes the cytoplasm, greatly increasing the surface area available for biochemical synthesis.
Endoplasmic reticulum (ER)
It serves as the site for synthesizing fatty acids and phospholipids.
Smooth ER
It serves as the site for synthesizing protein where it is studded with ribosomes.
Rough ER
Serves as sites where genetic information contained in mRNA is translated into proteins.
Ribosome
Are found in most eukaryotes, including both animal and plants, and are sites of the oxidative phases of cell respiration.
Mitochondrion
Cytoplasmic bodies, each located in a specialized region called the centrosome, are associated with the organization of spindle fibers that function in mitosis and meiosis.
Centrioles
Where centrioles are derived from. Associated with the formation of cilia and flagella (hair-like and whip-like structures for propelling cells or moving materials
Basal body
Play an important role in the movement of chromosomes as they separate during cell division.
Spindle fibers
Spindle fibers are made up of microtubules consisting of polymer of what protein?
Tubulin
What phase of the cell cycle wherein centrioles start to organize spindle fiber?
Prophase
Are the spindle fibers that are most directly responsible for chromosome migration by making contact with, and adhering to the kinetochore as they grow out of the centrosome region.
Kinetochore microtubules
Are found in plants, algae, and some protozoans, are associated with photosynthesis, the major energy-trapping process on Earth.
Chloroplast
In addition to the plasma membrane, plant cells also have what structure that is made primarily of polysaccharides known as cellulose.
Cell wall
Covering over the plasma membrane of animal cells consisting of glycoproteins, and polysaccharides. It provides biochemical identity at the surface of cells.
Glycocalyx or Cell Coat
These molecules act as recognition sites that transfer specific chemical signals across the cell membrane.
Receptor molecules
Constricted region on the chromosome, whose location establishes the general appearance of each chromosome
Centromere
The shorter arm of a chromosome.
p arm
The longer arm of a chromosome.
q arm
A chromosome whose centromere is located in the middle of the chromosome.
Metacentric chromosome
A chromosome whose centromere is located between the middle and the end.
Submetacentric chromosome
A chromosome whose centromere is located close to the end.
Acrocentric
A chromosome whose centromere is located at the very end.
Telocentric
DNA diameter
2 nm
Made of 2 units of histone octamer each wrapped with 147 DNA base pairs, and a unit of H1 histone wrapped with DNA spacer.
Nucleosome
Nucleosome size
6 nm X 11 nm flat disk
Made of 6 units of histone octamer each wrapped with 147 DNA pairs, and 6 units of H1 histone each wrapped with spacer DNA.
Solenoid
Solenoid size
30 nm
Composed of several solenoid units that are tightly looped.
Looped domain
Size of the looped domain
80-100 nm
Composed of several tightly looped domains.
Chromatin fiber
Size of Chromatin fiber
300 nm
What phase of the cell cycle is the chromosome most visible.
M phase
True or False. Somatic cells derived from members of the same species contain an identical number of chromosomes (diploid number, 2n)
True
Is a pair of chromosomes whose centromere location, size, and gene loci are identical.
Homologous chromosomes
Gene sites found on chromosomes.
Locus (plural. loci)
Alternative forms of a gene are called?
Alleles
True or False. The locus for a specific gene is present in both pairs of homologous chromosomes but they need not be identical in genetic sequence.
True.
Inheritance from two parents is called?
Biparental inheritance
Collection of all the genetic information contained in a haploid set of chromosomes.
Genome
True or False. Sex determining chromosomes (e.g. the X and Y chromosomes in humans) are not homologous in size, centromere placement, arm ratio, or genetic content.
True
True or False. Y chromosome humans are considerably smaller and lack most of the gene loci contained on the X.
True
The non-dividing phase of the cell cycle. Interval between divisions.
Interphase
What phase of the cell cycle does the cell exhibit cell growth, synthesis of proteins, and lasts about 5 hours in human cells?
G1 phase
True or False. Cells that enter G0 remain viable and metabolically active but are not proliferative.
True
True or False. Cancer cells apparently avoid entering G0 or pass through it very quickly.
True
What are the two pathways a cell in the G1 phase can proceed to?
- withdraw from the cell cycle, enter G0, and become quiescent.
- Become committed to proceed through G1, and initiate DNA synthesis.
True or False. Other cells enter G0 and never reenter the cell cycle. Still, other cells in G0 can be stimulated to return to G1 and thereby reenter the cell cycle.
True.
Lasts about 5 hours in humans.
G1 phase
Replication of the DNA (DNA synthesis) happens at what phase of the cell cycle.
S phase
Lasts about 7 hours in human cells.
S phase
In this phase, the cell undergoes further growth.
G2 phase
Lasts about 3 hours in humans.
G2 phase
Mitosis lasts how many hours in total?
1 hour
By the end of what phase the volume of the cell has roughly doubled, DNA has been replicated, and mitosis (M) is initiated.
G2 phase
What protein binds sister chromatids together?
Cohesin
In what phase of the cell cycle is cohesin formed?
S phase
Two pairs of centrioles migrate at the opposite poles of the cell, nuclear membrane, and nucleolus begin to disintegrate, and diffuse chromatin fibers have begun to condense.
Prophase
Area of differentiated cytoplasm where the centrioles are situated.
Centrosome
True or False. Plants with few exemptions, fungi, and certain algae seem to lack centrioles but spindle fiber is still present.
True
Period of migration of the double structured chromosomes to the equatorial plane.
Prometaphase
Is the midline region of the cell, a plane that lies perpendicular to the axis established by the spindle fibers.
Metaphase plate/ Equatorial plane
An assembly of multilayered plates of protein associated with the centromere.
Kinetochore
Lasts about 36 minutes in human cells.
Prophase
Lasts about 3 minutes in human cells
Metaphase
Centromere aligns on the metaphase plate.
Metaphase
Once properly attached to the spindle fibers during metaphase, the sister chromatids are disassociated from each other by a protein called?
Separase
What protein family protects the cohesin from being degraded by separase at the centromeric regions during metaphase?
Shugoshins
Lasts about 3 minutes.
Anaphase
Centromere split and the daughter chromosomes migrate at opposite poles.
Anaphase
Disjunction happens during what phase of cell division.
Anaphase
The process by which sister chromatids during mitosis and meiosis two, and homologous chromosomes during meiosis one separate from each other.
Disjunction
Each migrating chromatids during anaphase, and anaphase 2 are called?
Daughter chromosome
Lasts about 18 minutes.
Telophase
Daughter chromosomes arrive at the poles; cytokinesis commences.
Telophase
The division or partitioning of the cytoplasm.
Cytokinesis
True or False. In animal cells, a cell plate is synthesized and laid down across the region of the metaphase plate during cytokinesis.
False
True or False. In animal cells, complete constriction of the cell membrane produces the cell furrow characteristic of newly divided cells.
True
The chromosomes begin to uncoil and become diffuse chromatin once again, while the nuclear envelope reforms around them, the spindle fibers disappear, and the nucleolus gradually reforms and becomes visible in the nucleus during early interphase. Reverse prophase.
Telophase
Serve as “master control” molecules functioning in conjunction with proteins called cyclins.
Kinases
These molecules can add phosphates to other proteins.
Kinases
Formed when cyclin binds to kinases activating them at appropriate times during the cell cycle.
Cyclin - Cyclin-dependent kinase complex
Control the proceeding of one stage of the cell cycle to another.
Cell cycle checkpoints
At this checkpoint, the cell monitors size and DNA integrity.
G1/S checkpoint
True or False. If the cell has not reached its optimum size, the cell is not allowed to proceed to the S phase. If the DNA is damaged, it has to be repaired first.
True
At this checkpoint, the cell monitors DNA synthesis and damage. It facilitates DNA repair if damage in the DNA is detected.
G2/M checkpoint
Cell monitors spindle formation and attachment to kinetochores.
M checkpoint
When does the cell decide to exit the cell cycle?
During G1 phase. G0 phase is at the middle of the G1 phase.
Cyclins and CDKs present in G0 phase.
Cyclin C, and CDK3
Cyclins and CDKs present in G1 phase.
Cyclins D, E, and CDKs 2, 4, 6
Cyclins and CDKs present in S phase.
Cyclins A, E, and CDK 2
Cyclins and CDKs present in G2 phase.
Cyclin A, CDKs 1, 2
Cyclins and CDKs present in M phase.
Cyclin B, CDK1
Genetic material during leptonema is called?
Chromomeres
During this phase of prophase 1 of meiosis, paternally and maternally derived chromosomes undergo homology search.
Leptonema
Genetic material during zygonema is called?
Bivalent
During this phase of prophase 1 of meiosis, homologous chromosomes pair off or undergo synapsis forming bivalent.
Zygonema
Process wherein homologous chromosomes pair off.
Synapsis
True or False. The number of bivalents is equal to the diploid number of chromosomes.
False. Haploid number = bivalent number.
Homologous chromosomes undergo thickening and doubling to form a tetrad.
Pachynema
Consisting of two pairs of sister chromatids, each of which is joined at a common centromere.
Tetrad
Genetic information during the pachynema phase is called?
Tetrad
Formation of chiasmata.
Diplonema
Fragments from the maternal chromosomes exchange fragments from the paternal chromosome.
Crossing over
When does crossing over happen?
Diplonema of Prophase I
Chromosomes undergo terminalization.
Diakinesis
Homologous chromosomes that undergone crossing over align at the metaphase plate.
Metaphase I
During metaphase I, what structures are visible and appear to be the only factor associating the non-sister chromatids together?
Terminal chiastama
One-half of each tetrad (the dyad) is pulled toward each pole of the dividing cell.
Anaphase I
At the completion of a normal anaphase I, a series of dyads equal to ____ is present at each pole.
Haploid number of chromosomes
Nuclear membrane forming around the dyads. Chromosomes reach the opposite poles of the cell and cytokinesis proceeds.
Telophase I
This happens during faulty segregation during gamete, specifically during anaphase I and II.
Nondisjunction
This happens during Anaphase I where tetrads do not segregate causing one of the daughter cells to have 4 chromosomes and the other is deprived of any.
First division nondisjuction
This happens during Anaphase II where sister chromatids do not segregate causing one of the daughter cells to have 2 chromosomes and the other is deprived of any.
Second devision nondisjuction
The occurrence of this syndrome is correlated with maternal age because meiosis in females is arrested causing the ovum to be not renewed and aged. The aging process causes mutations that disrupt normal functioning.
Trisomy 21 (Down’s syndrome)
A condition caused by having an extra copy of chromosome 21.
Down syndrome (Trisomy 21)
A condition caused by having an extra copy of chromosome 18.
Edward’s syndrome (Trisomy 18)
A condition caused by having an extra copy of chromosome 13.
Patau’s syndrome (Trisomy 13)
A phenomenon common on plants but very rare in animals, and is often caused by hybridization.
Polyploidy
A condition of having multiple sets of haploid genes.
Polyploidy
Individual that has more than two sets chromosome set all derived from a single species.
Autopolyploid
Organism that resulted from viable mating between two different but closely related species.
Allopolyploid
A chemical reagent that breakdowns spindle fibers to prevent the chromosome from segregating.
Colchicine
Produces a metabolite called taxol that disrupts the production of spindle fibers.
Taxos brevifolia
Produces vinblastine and vincristine that disrupts spindle fiber formation.
Cantharanthus roseus
Products/metabolites of rosy periwinkle that are used to treat leukemia.
Vinblastine and vincristine
Mutations that are known to exert an effect at one or another stage of the cell cycle.
Cell division cycle mutation
