chapter 12 and 13 Flashcards
Define genome and state what major events must occur during cell division for the entire genome to be passed on to daughter cells.
genome- is the complete set of an organism DNA, including genes and non-coding sequences
DNA replication- ensures daughter cell receives full set of genetic material.
chromosome segregation- during mitosis and sister chromatids sepreate.
cytokinesis- physically divides the cell, separating the cytoplasm and organelles.
Distinguish between chromosome, chromatin, and sister chromatids.
chromosome- single DNA molecule with associated proteins carrying genetic info
chromatin- the relaxed uncondensed form of DNA found in the nucleus during interphase
sister chromatids- idenical copies of a chromosome joined together at the centromere formed after DNA replication.
List the phases of mitosis (prophase, metaphase, anaphase, telophase) and describe the sequence of events that occurs during each phase.
prophase- chromatids condense into visible chromosomes and nuclear envelope disappears and spindles form.
metaphase- chromosomes align at the metaphase plate and spindle fibres are attached to kinechores at the centromere.
anaphase- sister chromatids are pulled apart at opposite polls
telophase- chromosomes de-condese, nuclear envople reforms and spindles dissemble.
Describe what major events occur during the G1, S and G2 periods of interphase, and describe what characterizes a G2 interphase cell.
g1- cell growth, organelle duplication, and checkpoint control before DNA replication
s- DNA replication occurs
g2- preparation mitosis making sure everything goes smoothly
Compare cytokinesis in animals and plants.
animal cells- cleavage furrow forms due to actin-myosin contractions
plant cells- cell plate forms from Golgi vesicles, leading to new cell wall.
Describe the roles of checkpoints, cyclin, Cdk and MPF in the control of the cell cycle.
checkpoints- they are control points at g1, g2, and m phases
cyclin- regulatory protein whose concentration fluctuates,
cdks- activated by cyclin to regulate cell transitions.
MPF- cyclin-cdk complex that triggers mitosis
Explain how growth factors, density-dependent inhibition, and anchorage dependence influence cell division.
growth factors- proteins that signal the cells to divide
density- dependant inhibtion-cells stop dividing when crowded.
anchorage dependence-cells require attachment to surface to divide
Distinguish between asexual and sexual reproduction
asexual reproduction- is a single parent produces a genetically identical offspring.
sexual reproduction- two parents contribute genetic material to produce genetically different offspring.
Define the following terms: somatic cell, gamete, autosome, sex chromosome, karyotype, homologous chromosomes.
- somatic cell- any cell expect sex cell
- gamete-sex cells, eggg or sperm, haploid
- autosome- non-sex chromosomes, humans have 22 pairs
- sex chromosomes- chromosomes that determine sex x and y.
- karyotype- ordered display of chromosomes in a cell.
- homologous chromosomes- paried chromosomes, one from each parent, with some genes but different alleles.
Explain how haploid and diploid cells differ from each other. State which cells in the human body are diploid and which are haploid.
diploid (2n)- two sets of chromosomes, one from each parent, eg somatic cells
haploid (n)- one set of chromosomes- gametes
Recognize the phases of meiosis I and meiosis II and describe the events characteristic of each phase.
prophase 1- homologous chromosomes pair up (synapsis), forming tetrads, crossing over happens here too where there is a exchange of genetic material, spindle forms.
metaphase 1- homologous chromosomes pairs align at the metaphase plate and idependant assortment occurs here.
anaphase 1- homologous chromosomes separate, but sister chromatids stay attached.
telophase 1- two haploid daughter cells form
prophase 11- spindle reforms and nuclear envelope dissolves.
metaphase 11- chromosomes line up at the metaphase plate
anaphase 11- sister chromatids separate
telophase 11- four genetically unique haploid cells form.
Describe the process of synapsis during prophase I and explain how genetic recombination occurs.
synapsis- homologous chromosomes pair up forming tetrads.
crossing over- exchange of genetic material between non-sister chromatids at chiasmata is how this works.
Explain how independent assortment, crossing over and random fertilization contribute to genetic variation in sexually reproducing organisms.
independent assortment- homologous chromosomes randomly organize themselves creating different combinations.
crossing over- produces recombinant chromosomes mixed with partial alleles.
random fertilization- a sperm can inject any egg.
