Biology 1201A Lecture Notes - Lecture 1: Telomere, Intron, Centromere

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orchidshark702

18 Dec 2017

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Genome: the amount of dna in one complete set of chromosomes. Measured in amounts (mega base"s) or mass (pictogram"s) C-value paradox - no real relationship between the type or complexity of an organism and the amount of dna. Dna can also be found in chloroplasts and mitochondria. Karyotype: an organized image of all the chromosomes in a cell. Ploidy: the number of sets of chromosomes in the nucleus of a cell. Haploid: one set of chromosomes a baseline. In the karyotype of humans the haploid set is n=23. Humans are typically diploid (2n = 46) C-values and n-values are just characteristics used to describe a species. This is a large mutation in an individual and causes serious health problems. Draw a 2n = 6 cells (with c= 2. 5 pg) as it progresses through the cell cycle labelling at each phase": The majority of your genome does not code for proteins: 8% other important stuff ex. centromeres & telomeres.

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Ploidy refers to the number of complete sets of chromosomes (genes) present in a cell. The number of chromosomes in a complete set is a fixed characteristic of a species. Humans are diploid with two sets of 23 chromosomes. Fruit flies are diploid with two sets of 4 chromosomes. Sexually reproducing organisms are diploid, each somatic cell of an organism has two complete sets ("di" is a prefix indicating 2.). To complete a life cycle and reproduce new members of a species, mating is required. Mating brings a donation from a male and a donation from a female together. However, if the male and female cells remain diploid, the fertilization will result in a tetraploid zygote. In general, these are not viable. A mechanism is needed to form special haploid cells, gametes. The diploid set is split precisely into two complete haploid sets. That mechanism is meiosis.

The complete set of chromosomes of a species is also the complete set of genes of a species, the genome. (Yes, there is a minor contribution from mitochondria and chloroplasts. Inheritance of this information is "cytoplasmic".)

Please answer the following questions:

1. How many chromosomes in a brain cell of a fruit fly? How many chromosomes are in a liver cell of a human? Explain both answers.

2. How many chromosomes are in a fruit fly unfertilized egg? How many chromosomes are in a human egg? Explain both answers.

3. Why is meiosis necessary for sexually reproducing organisms? How many chromosomes are in a human zygote? Relate the two answers.

4. What is a gene allele? Suppose there is a gene called "bingo" and it is present once in a complete haploid set. How many alleles of "bingo" does a diploid individual have? How many copies or versions of the gene "bingo" are present in a diploid individual?

5. Modern DNA sequencing clearly identifies alleles by showing the different DNA sequence of each allele. These alleles may be termed structural alleles (I coined the term for this problem.). Classical genetics only dealt with phenotypes or visible traits. As a result, alleles of genes were identified by functionality, usually normal or non-functional. Using your knowledge of gene structure and gene expression, postulate a relationship between structural alleles and functional alleles. (include relative amounts; more, less, or equal).

M2A1 Worksheet: Mitosis and Meiosis

A dog is a diploid organisms and has 39 pairs of chromosomes (2n = 78), where n = 39 chromosomes from each parent. Use this example to answer the following question regarding chromosomal number.

INTERPHASE

How many chromosomes are present in the somatic cell?

What do they look like?

What are they âdoingâ in G1 of this phase?

What is happening in the S phase?

What is happening in the G2 phase?

What follows G2 phase in a somatic cell?

What follows G2 phase in a gamete cell?

MITOSIS

Number of chromosomes in the parent cell.

Number of chromatids in the parent cell.

Number of chromosomes in the daughter cell.

Number of chromatids in the daughter cell.

How many daughter cells are produced?

Are the daughter cells haploid or diploid?

How many cell divisions take place?

In what type of cell does this division occur?

Meiosis 1:

Number of chromosomes in the parent cell.

Number of chromatids in the parent cell.

Number of chromosomes in each Meiosis I daughter cell.

Number of chromatids in each Meiosis I daughter cell.

Are the daughter cells haploid or diploid at the end of Meiosis 1?

Meiosis II:

Number of chromosomes in the âparentâ cell (which is a daughter cell from Meiosis I).

Number of chromatids in the âparentâ cell.

Number of chromosomes in each Meiosis II daughter cell.

Number of chromatids in each Meiosis II daughter cell.

Are the daughter cells haploid or diploid at the end of Meiosis II?

Which phase or phases of Meiosis account for the genetic variability among the daughter cells? Howâ¦ what happens in this phase to create the diversity?

Comparing Mitosis and Meiosisâ¦..

How many daughter cells result from Mitosis? Are they diploid or haploid?

How many daughter cells result from Meiosis? Are they diploid or Haploid?

Cell structures and function: Match each organelle to its function:

Organelle Function

Lysosome 1. Lipid synthesis

Rough ER 2. Houses DNA

Nucleus 3. Energy extraction

Smooth ER 4. Dismantles debris

Golgi apparatus 5. detoxification

Mitochondria 6. Protein synthesis

Peroxisome 7. Processes secretions

What is the function of checkpoint proteins in the cell cycle?

How can all of a personâs cells contain exactly the same genetic material, yet specialize as bone cells, nerve cells, muscle cells and connective tissues?

What are the 3 primary germ layers?

Briefly, in one or two sentences, distinguish between

a bacterial cell and a eukaryotic cell

interphase and mitosis

mitosis and apoptosis

an autosome and a sex chromosome

homologous pair of chromosomes and a sister chromatid

centromere and centriole

chromosome and chromatid

monozygotic and dizygotic twins

allele and gene

6. When homologous chromosomes pair up in meiosis, this is called:

a.	replication.

synapsis.

c.	cytokinesis.

d.	segregation.

7. Energy that is stored is called:

a. potential energy.

b.	thermodynamic energy

c.	activation energy.

d.	kinetic energy.

8. The O2 that we inhale when we breathe:

a.	is used in the mitochondria in aerobic cellular respiration.

b.	All of the above are true of the O2 we inhale.

c.	acts as the terminal electron receptor at the end of aerobic cellular respiration.

d.	may be produced by plants through photosynthesis.

9. Photosynthesis is the process by which:

a.	carbon dioxide is synthesized.

b.	glucose is synthesized.

c.	plants burn energy.

d.	glucose and other molecules are broken down.

10. If there is no oxygen available for a eukaryotic cell, which of these chemical reactions involved in cellular respiration will take place?

a.	the Krebs Cycle.

b.	glycolysis.

c.	all three can occur without oxygen.

d.	the electron transport chain.

11. Eukaryotic chromosomes:

a.	all of the above

b.	contain DNA.

c.	contain the recipe for the proteins needed for life.

d.	contain genes.

12. The diploid (2N) number of chromosomes in humans is 46. The number of chromosomes found in a human sperm cell is:

b.	the haploid number cannot be determined from the information given

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Biology 1201A Lecture Notes - Lecture 1: Telomere, Intron, Centromere

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