Genes - Lecture 15 - Eukaryotic genetics Flashcards
What are the three domains of life?
Bacteria
Archaea
Eukarya
What is the definition of a gene?
A carrier of heritable information
How did complex life rise?
Energy was coupled with information which made way for symbiosis
This developed into complexible
What is the purpose of a telomere?
To stabilise the ends of chromosomes
How do telomeres stabilise the ends of chromosomes?
They have a loop structure called a T loop
This stops chromosomes from recombining with other DNA or fusing with other chromosomes
They shorten after each round of DNA replication and cell division
What is an alternative to a telemere?
Telomerase
Prevents the shortening of chromosomes
What is a eukaryote gene?
An inheritable sequence of DNA with an associated function that contributes to the phenotype of the organism during development
What are the two types of eukaryotic genomes?
Mitochondrial
Nuclear
What are some features of mitochondrial genomes?
DNA is coated with non-histone proteins
DNA is circular
Smaller DNA
Mitochondria is maternally inherited
Cytoplasmic inheritance
What are some features of nuclear genomes?
DNA and histone proteins that form chromatin
Nucleosome is the fundamental unit of chromatin
Genes are organised into chromosomes
Nuclear inheritance
What are the main features of a genome?
Have regulatory regions that are recognised by transcription factors
Coding where mRNA is translated into a protein
Non-coding but transcribed, RNAs like tRNA or rRNA are made
Intragenic, DNA sequences within genes
Intergenic, DNA sequences between genes
What is the function of mitosis?
Makes sure both daughter cells inherit one copy of the duplicated genome
What is the function of meiosis?
To make haploid gametes to allow for sexual reproduction, and increase genetic diversity by recombination
What are the two types of mitosis?
Symmetric
Asymmetric
What is symmetric mitosis?
Where there is only one type of cytoplasmic cell fate determinant
Two stem cells are created
What is asymmetric mitosis?
Where there are two types of cytoplasmic cell fate determinant
A stem cell and a differentiating cell are created
When does meiosis occur?
After G2, after the chromosomes have replicated
What are the main occurrences of meiosis 1?
Recombination
Homologous chromosomes are separated
Makes haploid daughter cells with two chromatids
What are the main occurrences in meiosis 2?
Divides the sister chromatids
Equational division
Makes haploid gametes with 1 chromatid
What are the three ways meiosis can influence genetic variation?
Independent assortment
Random fertilisation
Crossing over
What is independent assortment in meiosis?
It generates different combinations of chromosomes in gametes
2n different gametes can be generated
For humans this is around 8.4 million different gametes
What is random fertilisation in meiosis?
Many different combinations of egg and sperm
8.4 million different possible eggs and 8.4 million different possible sperm is 70 trillion different zygotes
What is crossing over in meiosis?
It generates new combinations of alleles on chromosomes
Involves the random pairing of homologous chromosomes
Occurs in prophase 1
Humans have 40-95 cross overs per meiosis
