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Chapter 7

The document outlines the structure and processes of several key components of cellular reproduction: ribosomes, tRNAs, crossing over during meiosis, recombinant formation, and random orientation in metaphase I. Ribosomes are composed of protein and rRNA subunits and bind mRNA and tRNAs. tRNAs are composed of nucleotides that attach to amino acids and have an anticodon site. Crossing over occurs as homologous chromosomes exchange DNA during meiosis I. Recombination forms during meiosis I as homologous chromosomes pair up and chiasmata form, allowing for crossing over. Random orientation of homologous chromosomes in metaphase I leads to genetic variation in haploid cells.

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45 views1 page

Chapter 7

The document outlines the structure and processes of several key components of cellular reproduction: ribosomes, tRNAs, crossing over during meiosis, recombinant formation, and random orientation in metaphase I. Ribosomes are composed of protein and rRNA subunits and bind mRNA and tRNAs. tRNAs are composed of nucleotides that attach to amino acids and have an anticodon site. Crossing over occurs as homologous chromosomes exchange DNA during meiosis I. Recombination forms during meiosis I as homologous chromosomes pair up and chiasmata form, allowing for crossing over. Random orientation of homologous chromosomes in metaphase I leads to genetic variation in haploid cells.

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We take content rights seriously. If you suspect this is your content, claim it here.
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Outline the structure of ribosome

- Made of protein and rRNA


- Large subunit and small subunit
- Three tRNA binding sites
- APE
- mRNA binding site
- 70s in prokaryotes, 80s in eukaryotes
- Can be free or bound to rER

Outline the structure of tRNA


- tRNA composed of one chain of nucleotides
- tRNA has a site attaching an amino acid at 3’ terminal
- tRNA has an anticodon
- Anticodon of three bases which are not base paired
- tRNA has double stranded sections formed by base pairing
- Double stranded sections can be helical
- tRNA has loops
- tRNA has a distinctive three dimensional clover leaf shape

Outline the process of crossing over


- Happens during prophase I of meiosis
- Homologous chromosomes exchange DNA
- Recombinants created

Outline the formation of recombinants during meiosis


- Recombination occurs in prophase I of meiosis
- Homologous chromosomes come together in pairs
- Chiasmata form between non-sister chromatids
- Crossing over takes place

Outline the random orientation in metaphase I leading to genetic variation


- When the chromosomes separate in meiosis to form haploid cells, there is random orientation of
homologous chromosomes to either each side of cell in metaphase I
- This is independent assortment of genes on different chromosome types
- Homologous chromosomes separate to opposite poles when attaching to spindle fibres
- There is 2n combinations of chromosomes, where n is the number of chromosomes pairs,
producing large genetic variation in haploid gametes
- There are effectively infinite number of combinations if effect of crossing over are included.

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