Topic 10 Flashcards
(23 cards)
What are the steps of Meiosis I?
Prophase I
Metaphase I
Anaphase I
Telophase I and Cytokinesis
What happens in Prophase I?
Chromosomes condense, homologous chromosomes pair up and crossing over occurs
What happens in Metaphase I?
Paired homologous chromosomes line up at the middle of the cell.
What happens in Anaphase I?
Homologous chromosomes are pulled apart to oppisite poles, reducing the chromsome number by half.
What happens during Telophase I and Cytokinesis?
The cell divides into two haploid cells, each with a set of sister chromatids.
What are the steps of Meiosis II?
Prophase II
Metaphase II
Anaphase II
Telophase II and Cytokinesis
What happens during Prophase II?
Chromosomes condense again in the daughter cells.
What happens during Metaphase II?
Chromosomes line up at the cells equator.
What happens during Anaphase II?
Sister chromatids are pulled apart to opposite poles.
What happens during Telaphase II and Cytokinesis?
The cells divide again, resulting in four genetically distinct haploid gametes.
Why does Meiosis I Non disjunction occur? What does it result in?
This occurs when homologous chromosomes fail to seperate properly.
Results in two gametes with an extra chromosome (n+1) and two gametes missing a chromosome (n-1)
Why does Meiosis II Non disjunction occur? What does it result in?
Occurs when sister chromatids fail to seperate.
Results in one gamete with an extra chromosome (n+1), one with a missing chromosome (n-1) and two normal gametes.
What are the consequences of nondisjunction?
Trisomy: presence of extra chromosome. Ex.downsyndrome
Monosomy: absence of a chromosome Ex. turners syndrome
Polyploidy: Entire sets of chromosomes fail to seperate-cells with muliple copies of each chromosome
Whats Chromatin?
DNA+histones+other proteins forming nucleosomes
Describe Open chromatin (Euchromatin)
Loosley packed, accesible to TFs and RNAP
Active transcription region
Describe Closed chromatin (Heterochromatin)
Tightly packed, less accesible to TFs and RNAP
Gene expression is typically silenced
What does Lysine/Arginine Acetylation do?
Neutralizes positive charge, reducing histone-DNA binding
What adds acetyl groups and promotes open chromatin?
HATS
What removes acetyl groups, promoting closed chromatin?
HDACS
_____________ at different lysine residues can either _______ or ________ chromatin.
METHYLATION at different lysine residues can either OPEN or CLOSE chromatin.
What is genetics?
The study of how genes being passed along through reproduction affect resulting traits in offspring.
What does epigenetics mean?
Epi genetics means above genetics- meaning, the regulation of chromatin state represents another way for cells to control phenotype.
What affect does chromatin state being hertiable have?
The effect is when chromsomes are replicated chromatin state is maintained in each of the resulting daughter chromosomes.
