Biology EOY D

Plant root/shoot cells

Meristematic cells, protected by root cap, are undifferentiated cells for growth

Yeast mitosis

Asexual reproduction through asymmetric division known as budding.

Unequal cell division causes outgrowth from parent cell, eventual detaching and becoming its own cell.

Animal cell cytokenisis

Contractile ring of actin and myosin proteins tightens around the cell, creating a cleavage furrow at the equator of the cell. Eventually, two daughter cells are formed.

Plant cell cytogenesis

Cell plate forms from vesicles at the equator, starting centrally and building outwards till the cell wall is reached. The first vesicles carry carbohydrates, lipids and proteins fusing together to create two plasma membranes. The final vesicles carry pectin and cellulose and deposit them by exocytosis in the gap forming a cell wall.

Oogenisis

Primary oocyte formed before birth (2n), separating by Meosis one first into a secondary oocyte (1n) and a polar body (1n) during puberty, then into a full ovum (1n) and a second polar body (1n) when the egg is fertilised.

Protein types and examples

Globular - hemoglobin

Fibrous - collagen

Ribosome sites

A (aminoacyl) site - entrance binding with the incoming tRNA

P (peptide) site - holds the tRNA carrying the growing polypeptide chain

E (exit) site - exit for the deacylated tRNA molecule to exit the ribosome

RNA types

mRNA - messenger RNA, carries genetic information from nucleus to ribosome (codon)

tRNA - transfer RNA, transporting amino acids to ribosome during translation (anticodon)

rRNA - ribosomal RNA, used in ribosome

DNA directions

3’ to 5’ direction of enzyme work

5’ to 3’ direction of synthesised daughter strand

RNA direction

5’ to 3’ direction of enzyme work

3’ to 5’ direction of synthesised daughter strand

Types of body cells

Somatic cell - any cell of a living organism other than the reproductive cells.

Germ cell - reproductive cell of an organism

Taq polymerase

Taq polymerase is isolated from the thermophilic bacterium Thermus aquaticus

As this enzyme’s optimal temperature is ~75ºC, it is able to function at the high temperatures used in PCR without denaturing

PCR process

Denaturation – DNA sample is heated to 90ºC to separate the two strands

Annealing – Sample is cooled to 55ºC to allow primers to anneal

Elongation – Sample is heated to the optimal temperature for a heat-tolerant polymerase (Taq) to function at 75ºC

The cycle repeats (takes about 2 mins each)

30 cycles creates over 1 billion copies (2³⁰)

Types of mutation

Substitution - e.g, ATG becomes ACG

Inversion - e.g, ATG becomes AGT

Insertion - e.g, ATG becomes ATCG (changes reading frame)

Deletion - e.g, ATG becomes AG (changes reading frame)

Effects of mutations

Silent - doese’t alter amino acid sequence due to degeneracy of genetic code

Missense - alters a single amino acid (can cause sickle cell anaemia)

Nonsense - causes premature stop codon (can cause cystic fibrosis)

Framshift - change in reading frame effecting entire sequence

Human Genome Project

Sequencing of entire human genome.

Enabled the development of personalized medicine

Improved our understanding of inherited diseases,

Facilitated advancements in cancer research and gene therapy.

Genome definiton

The total genetic information of a cell, organism or organelle

Proteome definition

Entire complement of proteins that is or can be expressed by a cell, tissue, or organism.

Transcriptome definition

The sum total of all the messenger RNA molecules expressed from the genes of an organism.

Methylation types

DNA methylation - decreases gene expression by preventing binding of transcription factors

Histone methylation - affects how tightly DNA is packed around the histone.

DNA transcription factors

Activator proteins bind to enhancer sites increasing transcription rates

Repressor proteins bind to silencer sequences decreasing transcription rates

CRISPR

Clustered regularly interspaced short palindromic repeats.

Mitosis

Meosis

Cell cycle and regulation

DNA replication