Genes - Lecture 15 - Eukaryotic genetics

Question 1

What are the three domains of life?

Answer 1

Bacteria
Archaea
Eukarya

Question 2

What is the definition of a gene?

Answer 2

A carrier of heritable information

Question 3

How did complex life rise?

Answer 3

Energy was coupled with information which made way for symbiosis
This developed into complexible

Question 4

What is the purpose of a telomere?

Answer 4

To stabilise the ends of chromosomes

Question 5

How do telomeres stabilise the ends of chromosomes?

Answer 5

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

Question 6

What is an alternative to a telemere?

Answer 6

Telomerase
Prevents the shortening of chromosomes

Question 7

What is a eukaryote gene?

Answer 7

An inheritable sequence of DNA with an associated function that contributes to the phenotype of the organism during development

Question 8

What are the two types of eukaryotic genomes?

Answer 8

Mitochondrial
Nuclear

Question 9

What are some features of mitochondrial genomes?

Answer 9

DNA is coated with non-histone proteins
DNA is circular
Smaller DNA
Mitochondria is maternally inherited
Cytoplasmic inheritance

Question 10

What are some features of nuclear genomes?

Answer 10

DNA and histone proteins that form chromatin
Nucleosome is the fundamental unit of chromatin
Genes are organised into chromosomes
Nuclear inheritance

Question 11

What are the main features of a genome?

Answer 11

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

Question 12

What is the function of mitosis?

Answer 12

Makes sure both daughter cells inherit one copy of the duplicated genome

Question 13

What is the function of meiosis?

Answer 13

To make haploid gametes to allow for sexual reproduction, and increase genetic diversity by recombination

Question 14

What are the two types of mitosis?

Answer 14

Symmetric
Asymmetric

Question 15

What is symmetric mitosis?

Answer 15

Where there is only one type of cytoplasmic cell fate determinant
Two stem cells are created

Question 16

What is asymmetric mitosis?

Answer 16

Where there are two types of cytoplasmic cell fate determinant
A stem cell and a differentiating cell are created

Question 17

When does meiosis occur?

Answer 17

After G2, after the chromosomes have replicated

Question 18

What are the main occurrences of meiosis 1?

Answer 18

Recombination
Homologous chromosomes are separated
Makes haploid daughter cells with two chromatids

Question 19

What are the main occurrences in meiosis 2?

Answer 19

Divides the sister chromatids
Equational division
Makes haploid gametes with 1 chromatid

Question 20

What are the three ways meiosis can influence genetic variation?

Answer 20

Independent assortment
Random fertilisation
Crossing over

Question 21

What is independent assortment in meiosis?

Answer 21

It generates different combinations of chromosomes in gametes
2n different gametes can be generated
For humans this is around 8.4 million different gametes

Question 22

What is random fertilisation in meiosis?

Answer 22

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

Question 23

What is crossing over in meiosis?

Answer 23

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