Exam 4 - Exam 4 I. II. III. IV. V. VI. How many chromosomes...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Exam 4 I. How many chromosomes are required to have one copy of each gene? Or how many chromosomes are required to have one complete copy of all the DNA needed to code for every protein in an organism? a. In humans, 23 chromosomes II. Does it matter which species we talk about? a. Yes because some organisms only require 1 or 2 chromosomes. There is a huge range III.Ploidy a. Number of sets of chromosomes i. Haploid = 1 set 1n ii. Diploid = 2 sets 2n iii. Triploid = 3 sets 3n iv. Tetraploid = 4 sets 4n IV.Polyploidy versus Aneuploid a. Polyploidy i. More than two sets of chromosomes b. Aneuploid i. Change in the number of a single chromosome (Down’s Syndrome) V. Homologous Chromosome a. Same length b. Same centromere position c. Same banding pattern d. Same genes** VI.Meiosis a. Produces non-identical daughter cells i. Mitosis (identical daughter cells)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
b. Half the number of chromosomes c. Why only half the number of chromosomes? i. Sexual reproduction d. Does it matter which chromosomes are in each daughter cell? i. Yes e. Stages i. Prophase 1 1. Most difficult stage 2. Homologous chromosomes in synapsis a. Tretrad formation = 4 chromatids present b. Chiasmata = place where chromosomes touch each other c. Crossing over 3. a. Mitosis is Pairs of chromosomes are on separate spindles b. Pairs are on the same spindle ii. Two important events 1. Segregation a. Homologous chromosomes separate into different daughter cells i. Happens in first division of Meiosis 2. Independent Assortment a. States that the pairs of chromosomes assort independently from one another iii. A cell in G1 of the cell cycle has 12 chromosomes in homologous pairs. It undergoes Meiosis, during Metaphase II each cell would contain? 1. 6 chromosomes with no pairs 2. 6 chromosomes with 3 pairs 3. 12 chromosomes with no pairs
Background image of page 2
4. 12 chromosomes with 6 pairs a. If we start a cell with diploids, we would have half the starting number with no pairs! iv. Figure 13.8 v. One of the 4 cells will actually be a sexual gamete f. If the first division of meiosis results in haploid cells, why do the second division? i. Crossing-over and the production of non-identical sister chromosomes VII. Life cycles (meiosis) a. Alternation of generations b. Organisms with multi-cellular haploid and diploid stages c. Spores produce a free living organism and is a product of Meiosis d. Sometime between fertilization and back to it again, you have to go through meiosis no matter what kind of organism for life cycles. VIII. Inheritance a. What happens as a result of moving all the DNA around? b. Reproduction: i. What is the outcome of asexual? 1. Identical offspring (mitosis) ii. What is the outcome of sexual? 1. Different offspring (meiosis) c. Key Points i. What is the role of the parent? 1. Produce gametes (link back to meiosis) ii. What type of cell division produces gametes?
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/26/2009 for the course BIOL 1201 taught by Professor Wishtichusen during the Fall '07 term at LSU.

Page1 / 19

Exam 4 - Exam 4 I. II. III. IV. V. VI. How many chromosomes...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online