Practical #1

Question 1

What are the commonalities between prokaryotic and Eukaryotic Cells?

Answer 1

Plasma membrane, All cells contain chromosomes, all cells have ribosomes, call cells have a fluid medium

Question 2

Briefly describe the interphase:

Answer 2

1. G1 (First Gap)
   
   1. Cell prepares for the replication of DNA
2. S (Synthesis of DNA)
   
   1. DNA is duplicated
   2. Each chromosome has 2 sister chromatids
3. Prepares for cell division by producing the components for the spindle apparatus

Question 3

What are the 2 components of Cell division?

Answer 3

1. Nuclear Division
   
   1. Mitosis
   2. Meiosis
2. Cytoplasmic division
   
   1. Cytokinesis

Question 4

Somatic Cells

Answer 4

Make up all of the cells of the animals body, except the gamete-producing cells (Non-reproductive cells)

Question 5

What is a step breakdown of gamete -> Zygote

Answer 5

• Fertilization
  
  • ​the process of fusing two gametes together
• Plasmogamy
  
  • ​the cytoplasm of the two gametes fuse
• Karyogamy
  
  • ​the two gamete nuclei fuse
• = Zygote

Question 6

Sexual Reproduction

Answer 6

• process where two paretns give rise to offspring through the fusion of gametes produced by meiosis
• Offspring have a unique combination of genees inherited from parents
• Are not gentically identical to either parent
  
  • has 1/2 the genes of each parent

Question 7

Prophase (Mitosis)

Answer 7

• Chromosomes condense
• The nuclear membrane and bucleolus disappera
• Centrioles move to cell poles

Question 8

Metaphase (Mitosis)

Answer 8

• The chromosomes move and line up at the center of the cell
  
  • metaphase plate

Question 9

Anaphase (Mitosis)

Answer 9

• The daughter chromosomes separate from each other at the centromere

Question 10

Telophase (Mitosis)

Answer 10

• Nuclear membrane forms around each collection of chromosomes
  
  • remember chromsomes traveled to poles in anaphase
• Nuclear membrane forms
• Chromosome begin to unwind and become chromatin

Question 11

Cytokinesis in Plants vs Animals

Answer 11

• Animals
  
  • Cleavage Furrow forms where the cell pinches into two by a ring of microfilaments around the cell equator
• Plants
  
  • The cell wall basically forms in the center of two nuclei and then splits the cell

Question 12

Prophase (Meiosis I)

Answer 12

• Homologous chromosomes pair up to form tetrads
  
  • synapsis
• Crossing over Happens!
• After crossing over, four chromatids now are genetically unique
• Spindle apparatus forms from microtubules that arise from each pole of the cell
  
  • Attach at kinetochores and can move tetrad around

Question 13

Crossing Over

Answer 13

• The exchange of corresponding segments of chromatids of homologous chromosomes
  
  • Happens at the chiasma (chiasmata)

Question 14

Metaphase (Meiosis I)

Answer 14

• Tetrads are arranged at metaphase plate
• Homologous pairs of chromosomes are aligned along the metaphase plate
  
  • not individual chromosomes

Question 15

Anaphase (Meiosis I)

Answer 15

• Homologous Chromosomes separate and are pulled toward opposite poles

Question 16

Telophase (Meiosis I)

Answer 16

• Chromosomes move to edges until there is a haploid set at each pole.
  
  • Cannot be called sister chromatids since they are not identical

Question 17

Prophase (Meiosis II)

Answer 17

• Spindle apparatus forms, attaches to kinetochores and moves the chromatids around

Question 18

Metaphase (Meiosis II)

Answer 18

• Chromatids arranged at metaphase plate

Question 19

Anaphase (Meiosis II)

Answer 19

• Each chromosome separate and the separate chromatids travel toward opposite poles
  
  • remember chromatids are not identical here

Question 20

Telophase (Meiosis II)

Answer 20

• Separated chromatids arrive at opposite poles
• Nuclear membranes reappear.
• Second round of cytokkinesis then divides cytoplasm
• At the end of meiosis - there are four haploid daughter cells

Question 21

Spermatogenesis

Answer 21

• Creation of sperm
• Results in 4 sperm
• Partioning of cytoplasm is equal

Question 22

Oogenesis

Answer 22

• Production of eggs
• Occurs in ovaries
• Results in 1 functional body
  
  • 2-4 polar bodies
• Partitioning of cytoplasm is unequal

Question 23

Steps of Oogenesis

Answer 23

• Oogonium
  
  • differentiates into primary oocyte
• Meiosis I
  
  • Secondary Oocyte
  • 1st polar body
• Meiosis II Starts
  
  • Ootid
  • 2nd polar body
• Ovum
• Meiosis II is not finished until sperm triggers it

Question 24

Steps of Spermatogenesis

Answer 24

• 1 spermatogonium differentiates into a primary spermatocyte
• Primary Spermatocyte undergoes meiosis I
  
  • producing two haploud secondary spermatocytes
• Secondary spermatocyte finished meiosis II
  
  • Produces 4 haploid spermatids
• Sperm or spermatozoan