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36 Cards in this Set
- Front
- Back
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asexual repro results from __ divisions and sexual repro involves __ divisions and __ |
mitotic cell divisions
meiotic cell divisions and fertilization
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what phase do cells spend the most time in ? Explain the 3 substages |
Interphase 1. G1 (Gap1) which the cell is actively growing and is metabolically very active. G0 is a variation of G1 and are cells that are destined to NEVER divide again 2. S (synthesis) DNA of the chromosome is replicated- each chromosome is a single piece of dna double helix and is said to be single stranded. in this stage the replication allows the cells to become double stranded 3. G2 cells prepare for the actual cell division |
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what do mitotic cell divisions produce? and what kind of process is this? What are the divisions ? (4) |
- 2 genetically identical daughter cells from one original mother cell - continuous (one stage blends into the next)
- prophase (meta prophase),metaphase, anaphase, telophase
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explain prophase |
Nucleolus disappears, the spindle apparatus is assembled across the nuclear region (essential for proper functioning of the cell divisions), |
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what do animal cells have that plant cells do not |
- astral rays - animal cell cytokinesis occurs by cleavage furrow formation and in plants occurs by cell plate formation - higher plant and fungal cells lack centrioles |
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explain prometaphase |
nuclear membrane breaks down and the spindle fibers are able to penetrate the nuclear region, chromosomes condense, chromatids joined by a centromere, 2 kinetochores (primary constriction of the chromosome) |
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in prometaphase what are the 2 types of spindle fibers ? |
1. kinetochore fibers- they extend from one pole to the kinetochore of a chromosome 2. nonkinetochore spindle fibers- those that do not interact with the chromosomes
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explain metaphase |
short stage- alignment of all the centromeres on the equatorial plane, spindle is fully formed |
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explain anaphase and the movement |
begins with the centromere producing 2 single stranded chromosomes; the kinetochore spindle fibers pull away the newly formed daughter chromosomes toward the opposite poles, -depolymerization takes place at the kinetochore end of the microtubule and the kinetochore is somehow able to hold onto the shortening end of the spindle fiber leading to the movment of the chromosome towards the pole of the cell |
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Explain telophase |
nuclear membrane reforms, nucleolus re-appears and the spindle apparatus, and astral rays disappear, cytokinesis (division of the cytoplasm) occurs concurrently with telophase |
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what are the advantages and disadvantages of mitosis? |
advantage: very rapid, energy efficient without the requirements of a mate disadvantages: there's no genetic variability |
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what does meiotic cell divisions consist of? and in what type of cell? |
longer than mitotic cell divisions and is more complex, two consecutive nuclear divisions with NO dna replication- which results in the halving of the DNA content and the chromosomes number of the cell
- only in diploid cells (one of maternal origin, the other of paternal origin) the two chromosomes are called homologues |
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explain the two types of divisions in meiosis |
Meiosis I= the reuction divions that reduces the chromosome number by one half
Meiosis 2= is the equational division and is a mitotic like division, producing cells with single-stranded chromosomes |
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what are the 4 substages in prophase I for meiosis |
Leptonene, zygotene, pachytene, diplotene, diakinesis |
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what is lateral element |
in the leptotene stage- the chromatin appears to be condensing aroudn proteinaceous material that is known as the lateral element |
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in meiosis I during what stage is synapsis completed? and what is this event ? What are synapsed homologues called? |
in prophase I specifically the zygotene stage
- synapsis or pairing of homologous chromosomses
-bivalent |
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what happens in Pachytene stage? |
the presence of the sister chromatid is apparent for the first time
crossing over occurs- an actual breakage of the DNA strands and an exchange of non-sister chromatid fragments (important for genetic variability) |
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what is the physical manifestation of the crossing over event visible in the light microscope called? |
Chiasma |
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during anaphase I how many chromosomes will be present? |
half the original number of chromosomes |
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what occurs in telophase I |
Interkinesis- short interlude between meiosis I and II which is similar to interphase except that there is NO DNA replication (since they are double stranded) |
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what are centrioles composed of ? and what are spindle fibers? |
9 triplets of microtubules
individual microtubules |
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what are Mendels 2 laws? |
Law of segregation - monohybrid cross
2. Law of independent assortment - dyhibrid cross (analysis of 2 characteristics) |
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what are restriction enzymes? |
are isolated from bacteria and blue-green algae and in these organisms their function is to recognize and degrade foreign DNA, usually that of infecting viruses |
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Explain the 3 cuts and who makes them for an example |
1. staggered cut- EcoRI
2. Rd cuts- HindIII (what we used)
3. Blunt cut- HaeIII |
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what is a plasmid
why do geneticists use plasmids? |
small, autonomously replicating DNA molecules found naturally in bacteria. Bacteria will only replicate if it gains some advantage
used to amplify genes |
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what are the 2 different dyes used in restriction enzymes and what are the functions of these |
1. Tracking dye- terminates reaction of restriction enzyme, sample must be heavier than buffer, visually to tell if electrophoresis is happening so you can track progress
2. Cyber dye - everywhere there's dna there will be cyber to the dye is used to visually track dna |
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what is the method of agarose gel? |
to distinguish by size. All samples will be pulled into sugar matrix (smaller moves faster)
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what is the function of samples of known size? |
when this runs you can compare the samples of the unknown to get base pair size
for the molecular weight ladder (kilobase ladder standard) |
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what are 2 advantages and disadvantages of using microorganisms (lab 4) |
adv: easy to culture, rapid lifecycles, small
dis: counting can be time consuming, aseptic techniques are time consuming, pathogenic |
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what are the 2 methods to estimate cell denisty counts (lab 4) |
1. viable cell counts- only living (plate count method) 2. total cell counts- dead and living |
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what is conjugation |
the transfer of genetic material from a donor bacterial cell to a recipient cell following contact and the establishment of a conjugation tube between them |
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what do the donor strains carry and explain what it is (lab 4) |
donor strains carry F+ and recipient strains lack this.
Fertility factor is an episome, which means that it can integrate into the main bacterial chromosome or act as an independent plasmid
strains carrying F are HFR (high frequency of recombination) |
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what were the strains used in experiment 4 and what does the ending mixture look like? |
hfr= thr+leu+thi+lac+STR(s) f- = thr-leu-thi-lac-STR(r) (resistant to antibody)
mix= thr+leu+thi+/-STR(r) (the medium contains glucose as a carbon source so that the recombinants can be either +/- lac |
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what is the purpose of examining the growth of the original strains on the YPD plate? (lab 5) |
to see that the strains were not deficient and could grow on complete medium. Then when tested for deficiencies on YMM plate you can tell when there is a deficiency of using minimal medium. |
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what is true breeding? |
when the two organisms you are mating are homozygous for the trait you are examining |
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what are the 4 limitations for the hardy-weinberg model? and explain what each are |
1. mutation: origin of genetic variation. the ultimate source of genetic variation upon which the other factors can exert their force on 2. natural selection:acts upon the diversity of organisms and leads to greater adaptation of organisms to their environment 3. migration/geneflow: introduction of genes from one population to another 4. genetic drift: random change in the allele frequency. Happens when the allele freq. appearing in the offspring are not completely representative of the allele freq. found in the parents |
