Bio 160 Long Answer Questions

during this, genetic material is randomly separated and reorganized so that the daughter cells differ genetically from one another - Thus generates genetic diversity that is raw material for natural selection and evolution

- Reproductive signal
-Organelles & membrane must be formed
- Segregation
- Enzymes needed for cell division must be synthesized,
- Replication of DNA

DNA replication
segregation
cytokinesis

G1 - variable, cell generally spends long time carrying out specialized functions
S - DNA is replicated
G2 - cell makes preparations for mitosis

prophase, prometaphase, metaphase, anaphase, and telophase

- Condensed chromosomes
- Centrosome
- Spindle

• Determines a cells orientation by their position, will be where cell divides
• Consists of a pair of centrioles
- Hollow tube formed by 9 triplets of microtubules
• Becomes duplicated during S phase
• Determine spatial relationship between 2 new cells
• Plant cells lack centrosomes but have a similar structure

Two centrosomes when positioned on opposite sides of nucleus, create a pole, toward which the chromosomes move

Tubulin dimers from around the centrosomes aggregate into microtubules that extend in the middle of the cell
Two types
- Polar microtubules - form framework and run from one pole to another, keeping poles apart
- Kinetochore microtubules - form later, attach to kinetochores on chromosomes.
§ Sister chromatids in each chromosome attached to kinetochore microtubules from opposite sides of cell
□ Ensures that chromatids will be pulled toward opposite poles

Occurs during telophase
Animal Cells -
Divide via a contractile ring made of actin microfilaments (cleavage furrow)

Plant cells - vesicles fuse to form a cell plate (because plant cells have cell walls)


Following cytokinesis, each daughter cell contains all the components of a complete cell

- Reduce chromosome number from diploid to haploid
- Ensure each of the haploid products has a complete set of chromosomes
- To generate genetic diversity among the products

PPMAT

meiosis - reduces
- different prophase and anaphase I (homologous pairs)
mitosis - maintains
- (sister chromatids) in anaphase and prophase

Because of meiosis, each gamete receives a haploid # of chromosomes therefore a zygote receives 1 set from father and 1 set from mother.

alleles of different genes assort independently of one another during gamete formation.

• Mendel studied botany and mathematics at the university level before becoming a monk
• Experimentation with pea plant inheritance took place in the monastery garden
• Mendel’s background allowed him to see patterns in the way plant characteristics were inherited

a mechanism for transfer of genetic information in bacteria in which pure DNA from a bacterium of one genotype is taken in through the cell surface of a bacterium of a different genotype and incorporated into the chromosome of the recipient cell. ALSO, Insertion of recombinant DNA into a host cell
Bacterium strain A + strain B DNA -> bacterium strain B

Dexoxyribose
Phosphate Group
Nitrogen base (ATCG)

Purine (two carbon rings, A+G) paired with pyridimine (one carbon ring, C+T)

Helical - spiral shape like a string
Anti-parallel - the strands run in opposite direction

1. IT is a double stranded helix of uniform diameter
2. It is right handed
3. It is antiparallel
DNA is a double stranded molecule with the two strands lying antiparallel to each other (they lie parallel to each other but run in opposite directions)

4. The outer edges of the nitrogenous bases are exposed in the major and minor grooves

1. Storage of genetic information
2. Precise replication during the cell cycle
3. Susceptibility to mutations
4. Expression of the coded information as phenotypes

Okazaki discovered the way in which the lagging strand of DNA is replicated via fragments by conducting an experiment using E. coli.

Griffith discovered that a harmless strain of Streptococcus pneumoniae could be made virulent after being exposed to heat-killed virulent strains. Griffith hypothesized that some "transforming principle" from the heat-killed strain was responsible for making the harmless strain virulent.

Led to theory of transformation

Hershey and Chase used T2 phage, a bacteriophage, for their experiments. The phage infects a bacterium by attaching to it and injecting its genetic material into it.
They put labels on phage DNA with radioactive Phosphorus-32. They then followed the phages while they infected E. coli. They found that the radioactive element was only in the bacteria, and not in the phage.
In a second experiment, they put labels on the phage protein with radioactive Sulfur-35. After the phage was attached to the bacterium, the radioactive element was found in the phage, but not in the bacteria. This showed them that genetic material which infects the bacteria is DNA.

Significance is that it showed that DNA is genetic information, not proteins.

The basis for x-linked traits is the genes carried on one sex chromosome. X-linked inheritance is when the X chromosome carries more genes than the Y chromosome, thus a gene at a locus where there is no corresponding Y chromosome will express itself even if recessive. Autosomes are any chromosome that is not a sex chromosome