BIO152H5 Lecture : bio152 lec 5.docx

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coralhare22

1 May 2012

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Unicellular organisms: reproduction multicellular organisms: growth + maintenance of tissues (repair) + reproduction. Dna replication: cell elongates, splits into 2 daughter cells. Organisms splits int o2 and ech part becomes a complete organism (clone- genetically identical daughter cells). Chromosome replicates, chromosome pull apart, ring of ftsz protein forms ftsz ring contstricts, membrane + cell wall infold, fission is complete. Reproduction may stop under adverse nutritional conditions (require nutrients or go dormant) Metabolic activities depend on environment --> speed up ex. Eukaryotic cells contain genetic material in the nucleus of cells. Chromosomes: gene carrying structures consisting of a long molecule of dna + associated proteins (histones) Gene: section of dna encodes information for building polypeptides. Carry same genes in same locations, but each one may have diff alleles. Allele: different version of specific gene ex. Haploid (23)l cells contain just one of each type of chromosome. Diploid (46): cells contain two versions of each type of chromosome from each parent.

Related Questions

The DNA copying enzymes have a hard time working to the end of achromosome. For circular chromosomes this is not a problem, sincethere is not a sharp 'end'. However, for a linear chromosome,without extra mechanisms in place, a bit of DNA is lost off the endof the chromosome after each replication. Because of this,eukaryotes have a telomere to cap off their chromosomes.

In most cells of a mutli-cellular organism, this telomere isslowly worn away after each reproduction leading to apoptosis.Cells that need to reproduce indefinitely such as germ and stemcells have to invest in extra mechanisms to replenish the telomere.For multi-cellular eukaryotes I can see how this might be usefull(for instance as a cancer counter mechanism). However,multi-cellular organisms evolved from single-cell eukaryotes.

I cannot see a reason for wanting apoptosis in a single-cellorganism. However, single cell eukaryotes (say yeast) still havelinear chromosomes with telomere caps. What advantage did linearchromosomes provide single-cell eukaryotes to offset the extrainvestment in reparing the telomere?

Part A:

In prokaryotes and eukaryotes cell reproduction is similar in that it requires some kind of signal to proceed, DNA replication, careful separation of the DNA into two equal portions, and division of the cytoplasm. How is cell reproduction different in prokaryotes and eukaryotes?

Select one:

a. In a eukaryotic organism, the signals for cell division are usually not related to the environment but to the function of the entire organism.

b. Eukaryotic cells constantly divide whenever environmental conditions are adequate and the cells are large enough.

c. The linear chromosomes in prokaryotes are constantly being updated.

d. Prokaryotic cell division requires cytokinesis before mitosis because of their small size.

e. The sexual phase of most prokaryotes (bacteria) is essential to the rapid cell division required for infection.

Part B:

What does the name Cyclin Dependent Kinase stand for?

Select one:

a. A protein important to the cell cycle that is dependent on DNA synthesis.

b. An enzyme that cuts DNA so that chromosomes can segregate.

c. An enzyme that phosphorylates other proteins using ATP only when the protein Cyclin is bound to the enzyme.

d. An enzyme that rolls along microtubules dragging a vesicle.

e. An enzyme that connects chromosomes to the spindle fiber.

Part C:

The Cell Cycle is divided into Mitosis, Cytokinesis, and Interphase. Mitosis can be ordered into the following phases:

Select one:

a. Prophase/Prometaphase/Metaphase/Anaphase/Telophase

b. Anaphase/Prometaphase/Metaphase/Prophase/Telophase

c. Metaphase/Anaphase/Telophase/Prophase/Prometaphase

d. Telophase/Prophase/Prometaphase/Metaphase/Anaphase

e. Anaphase/Telophase/Prophase/Prometaphase/Metaphase

Part D:

The Cell Cycle is divided into Mitosis, Cytokinesis, and Interphase. Interphase can be ordered into the following phases:

Select one:

a. S/G1/G2

b. G2/G1/S

c. G1/S/G2

d. G2/S/G1

e. G1/G2/S

amethystyak657

Which of the following statements is NOT TRUE about chromosomes?

Prokaryotes have a singel, circular chromosome

Eukaryotes have multiple, linear chromosomes.

Human cells normally 23 pairs of chromosomes.

Eukaryote chromosomes are composed of only DNA

Which of the following is NOT TRUE about reproduction?

Eukaryotes life cycles include a haploid and diploid phase.

Prokaryotes reproduce asexually.

Eukaryotes can propagate by asexual or sexual reproduction.

Prokaryotes typically reproduce slower than eukaryotes.

Which of the folllowing animal cells is most likely haploid?

nerve cell

muscle cell

sperm cell

liver cell

When human gametes fuse, they form a _____.

		Haploid egg
		Diploid zygote
		Haploid zygote
		Triploid egg

BIO152H5 Lecture : bio152 lec 5.docx

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