Biology Ch 2. Reproduction Flashcards
Diploid
2n; cells have two copies of each chromosome
Haploid
n; cells have one copy of each chromosome
Interphase
Includes G1, S, G2, DNA is uncoiled in the form of chromatin for ease of replication, longest part of the cell cycle
G1 Stage
Presynthetic gap; cells create organelles for energy and protein production and increase their size, restriction point where DNA quality is checked occurs at the end of G1 before the cell can move on to S
S Stage
Synthesis; DNA is replicated and the chromatids are held together at the centromere
Chromatids
Each of the two chromosomal strands formed by DNA replication in the S phase of the cell cycle; held together by the centromere
G2 stage
Postsynthetic gap; further cell growth and replication of organelles in preparation for mitosis, another quality checkpoint at the end of this step
M stage
Mitosis; Mitosis and cytokinesis occur while DNA is tightly coiled in chromosomes to avoid losing any genetic material during cell division
G0 stage
Offshoot of G0 where cell performs its functions without preparing for division
p53
Protein that plays role in two major checkpoints of the cell cycle
Two major checkpoints of the cell cycle
G1 to S to determine if DNA quality is good enough for synthesis and G2 to M to ensure the cell has achieved adequate size and the organelles were properly replicated
Cyclins
Concentration rises and falls during the cell cycle, bind to CDKs to phosphorylate and activate transcription factors for next stage of cell cycle
Cyclin-dependant kinases (CDK)
Concentration rises and falls during the cell cycle, cyclins bind to them to phosphorylate and activate transcription factors for next stage of the cell cycle
Transcription factors mitosis
Promote transcription of genes required for the next cell cycles
Cancer
Occurs when the cell cycle becomes deranged, allowing damaged cells to undergo mitosis without regard to quality or quantity of the new cells produced, cancer cells may begin to product factors that allow them to delocalize and invade adjacent tissues elsewhere
Metastasis
Results from distant spread of cancerous cells throughout bloodstream or lymphatic systems
Mitosis
Produces two genetically identical diploid daughter cells from a single cell and occurs in somatic cells
Somatic cells
Perform mitosis to replicate, not involved in sexual reproduction
Mitosis phases
Prophase, metaphase, anaphase, telophase
Prophase
Chromatin condenses into chromosomes, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, spindle apparatus begins to form, spindle fibers contact each chromosomes kinetrochore
Metaphase
Chromosomes line up along the metaphase plate
Metaphase plate
aka equatorial plate, equidistant from two poles of the cell
Anaphase
Sister chromatids are separated and pulled to opposite poles when centromeres split into two and kinetochore fibers shorten
Telophase
Nuclear membrane reforms, spindle apparatus disappears, nucleoli reappear, cytokinesis occurs
Cytokinesis
Cytosol and organelles are split between the two daughter cells
Meiosis
Occurs in gametocytes and produces four nonidentical gametes, one round of replication and two rounds of division
Gametocytes
Germ cells
Gametes
Haploid sex cells
Meiosis rounds of division
The reductional division and the equational division
Meiosis I
Homologues come together, allow for crossing over, and then are separated from one another to result in haploid daughter cells, reductional division
Homologues
Chromosomes that are given the same number but are of opposite parental origin
Meiosis I steps
Prophase I, metaphase I, anaphase I, telophase I
Prophase I
Chromatin condenses into chromosomes, spindle apparatus forms, nucleoli and nuclear membrane disappears, homologues come together and intertwine during synapsis to form tetrad crossing over occurs (accounts for mendels second law - independent assortment)
Synapsis
Process where homologues come together and intertwine
Tetrad
Four chromatids together
Crossing over
When in a tetrad, genetic information is exchanged between one chromatid and its homologous chromosome
Mendel’s second law
aka law of independent assortment - crossing over accounts for it, states that inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes
Metaphase I
Homologous pairs (tetrads) line up on opposite sides of the metaphase plate when each pair is attached to a separated spindle fiber by its kinetochore
Anaphase I
Homologous chromosomes are pulled to opposite poles of the cell (accounts for mendels first law - segregation_
Mendels first law
aka law of segregation - anaphase I accounts for it, the distribution of homologies chromosomes to each intermediate daughter cell is random with respect to parental origin
Telophase I
Nuclear membrane reforms, chromosomes may or may not fully decondense and cell may enter interkinesis after cytokinesis
Interkinesis
Short rest period during which the chromosomes partially uncoil
Meiosis II
Sister chromatids are separated from each other in a process that is functionally identical to mitosis, equational division, no change in ploidy
Sister chromatids
Copies of the same DNA held together at the centromere
Cell cycle
A specific series of phases during which a cell grows, synthesizes DNA, and divides
Cell cycle stages
G1, S, G2, M
Chromatin
Less condensed form of DNA present during interphase
Centriole
A small organelle in the cytoplasm of animal cells; organizes the spindle apparatus during mitosis and meiosis
Centrosomes
Paired cylindrical organelles located in the cytoplasm that contain the centrioles, microtubule organizing center
Centromere
The area of a chromosome where sister chromatids are joined; also the point of attachment to the spinal fiber during mitosis and meiosis
Spindle fibers
Made of microtubules, radiate outward from the centrioles
Asters
Formed by some microtubules that anchor the centrioles to the cell membrane
Kinetochore fibers
Spindle fibers that extend towards middle of the cell, attached to kinetochores
Kinetochores
Protein striations at the centrosome that serve as attachment points for kinetochore fibers
Spindle apparatus
A structure within dividing cells composed of microtubules; it is involved in the separation of chromosomes during mitosis and meiosis
Synaptonemal complex
Group of proteins that holds homologous chromosomes together