Lesson 24: Review of working with sequence information/Heredity

If the DNA sequence is 5’CTCGATAGA’3 what is the complementary sequence 

3’GAGCTATCT’%

If the original sequence (5’CTCGATAGA’3) is part of the coding strand, what is the corresponding mRNA sequence

5’CUCGAUAGA’3

What are the three mechanisms to pass on genetic information and what are the types of cells/ organelles/production methods associated with them

1. Binary Fission (bacteria, mitochondria, chloroplasts)

2. Mitosis (eukaryotes, somatic cells, some single cell organisms 

3. Meiosis (eukaryotes, sexual reproduction, single-cell or multicellular) 

Explain binary mission 

During replication, chromosomes assort to opposite sides of the cell 

Chromosomes associate with proteins that anchor them to the poles 

Cell dives in the middle which paritions chromosomes 

Plasmids: small circular DNA molecules 

They are distributed equally more or less 

How do somatic eukaryotic cells reproduce (mitosis, cytokinesis)

Through asexual reproduction, so daugther cells are esentially clones

Mitosis: segregation of the DNA (nuclear division)

Cytokenisis: division of the cytoplasm 

Both rely on different temporary cytoskeletal machines: mitosis depends on miotic spindle formed by microtubules and cytokenisis machine is a contractile ring made of actin and myosin 

What does mitosis produce

2 identical daughter cells

Describe the 6 steps of mitosis

Interphase: Nuclear envelope is intact, chromosomes are decondensed (relaxed).Cell in g2 will progress to prophase 

Prophase: chromosomes begin to condense into miotic chromosomes (x shaped structure). Duplication, so each chromosome is coped which created the sister chromatids. Spindle begins to form outside the nucleus 

Prometaphase: Marked by disintegration of nuclear membrane. spindle attached to chromosome 

 Metaphase: chromosomes are lined up on the metaphase plate between the 2 poles 

Anaphase: sister chromatids seperate and move towards oppsotie poles. Cell is trying to get sets of chromosomes as far away as possible. As they arrie at spindle, contractice ring acts 

Telophase: chromosome arrive and spindles and nuclear membrane reforms, cell heading back to g1 

What does meiosis produce

4 seperate haploid gamete

What divisions does meiosis consist of, what is it the first step of, what does it increase

Meiosis 1- Reduction division: reduced chromosome number by half (typically go from 2n - n), separate homologous chromosomes

Meiosis 2 -Equational division: separate sister chromatids 

It is the first of sexual reproduction

Increases genetic variation: Crossing over of hoologous chromosomes. Rnadom separation of homologous chromosomes. 

When does replication occur in regards to meiosis 

Replication occurs prior to meiosis creating homologous chromosomes with 2 sister chromatids 

Describe meiosis

Prophase to metaphase to anaphase to telophase back to prophase, metaphase, anaphase, and telophase

What happens in meiosis 1: prophase

Chromosomes begin to condense, and the spindle forms

What happens in meiosis 1: Late prophase

Homologous chromosomes pair and crossing over takes place. Sister chromatids are no longer identical bc of crossing over (allelic shuffling). Nuclear envelope begins to breakdown.

What happens in meiosis 1: metaphase

homologous pairs line up chromosomes on metaphase plate

What happens in meiosis 1: anaphase

Anaphase 1: homologous pairs separate and move to opposite poles, still 2 sister chromatids but homologs are separated 

What happens in meiosis 1: telophase

Arrive at chromosome pole and chromosomes relax some. Now differnt combinations of paternal and maternal homols (result of independent assortment) DNA replication is supressed and heading into meiosis 2. 

What happens in meiosis 2: prophase

Chromosomes recondense

What happens in meiosis 2: Meiosis

Individual chromsomes line up on equatiorial plate.

What happens in meiosis 2: Anaphase

Chromosomes pop apart and move towards opposite poles (now sister chromatids)

What happens in meiosis 2: Telophase

Chromosomes begin to decondense. Nuclear envelope begins to form Produces 4 gametes, haploid cells.