BS 161 Lecture Notes - Lecture 20: Dna Replication, S Phase, Chromosome

62 views4 pages

byzantiumhound56

6 Apr 2019

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

A cell grows, replicates its dna and splits into two. Haploid = having a single set of unpaired chromosomes . Alleles: are the number of genes in an organism correlated with the number of chromosomes. One chromosome made up of a single dsdna is simply one double strand of. One chromosome with two chromatids is (what one chromosome after s-phase becomes. ) A ssdna is a single strand of dna. Cells put dividing on pause/they don"t divide: *know the relative amounts of dna in the various stages of the cell cycle. Understand the differences between different genes, an identical" copy of a gene, and alleles of the same gene. Homologous chromosomes are chromosome pairs in which one is from the father and one is from the mother. Different genes = different sections of dna. Alles of the same gene = different forms of a gene (ex. A centromere is a dna sequence where kinetochore proteins bind.

Related Questions

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

1. How does meiosis generate genetic diversity?

a) crossing over

b) random alignment at metaphase I

c) synapsis

d) both crossing over and random alignment at metaphase I

2. What would happen if crossing over occurred between sister chromatids?

a) Genetic diversity would decrease due to the loss of gene combinations.

b) Genetic diversity would increase due to the addition of gene combinations.

c) Gene rearrangement would lead to changes in gene expression.

d) Nothing would happen becasue sister chromatids are genetically identical or nearly identical.

3. Animals that sexually reproduce are _____ and produce _____ gametes. (haploid, diploid; haploid, haploid; diploid, diploid; diploid, haploid)

4. The F1 generation of a cross between two individuals, one that is homozygous dominant for a trait and the other that is homozygous recessive for the trait, will yield progeny with the same phenotype. (true or false)

5. Homologous chromosomes separate from each other in:

a) mitosis

b) meiosis I

c) meiosis II

d) They never separate from each other during any form of cell division

chocolatealpaca651

BS 161 Lecture Notes - Lecture 20: Dna Replication, S Phase, Chromosome

Document Summary

Get access

Related Documents

BS 161 Lecture 4: BS 161 01/16 DNA

BS 161 Lecture Notes - Lecture 27: Alternative Splicing, Complementary Dna, Small Interfering Rna

BS 161 Lecture Notes - Lecture 24: Semiconservative Replication, Isotopes Of Nitrogen, Okazaki Fragments

Related Questions