IMMS

Question 1

What is the difference between prokaryotes and eukaryotes

Answer 1

Prokaryotes have no nuclear membrane, all DNA in a single chromosome

Eukaryotes have their DNA within a nucleus. Some DNA in mitochondria

Question 2

Functions of DNA

Answer 2

Template for Transcription and Translation

Basis of Genetic Disease

Question 3

What is Mitosis

Answer 3

Process of cell division that creates 2 genetically identical daughter cells

Question 4

What are the phases of the cell cycle?

Answer 4

G1
S
G2
Mitosis

Question 5

What happens during G1?

Answer 5

Cell grows in size

Question 6

What happens during G2?

Answer 6

Proteins that are needed for cell division are produced

Question 7

What happens during S phase?

Answer 7

DNA replication

Question 8

What are the stages of Mitosis? (5)

Answer 8

Prophase
Prometaphase
Metaphase
Anaphase 
Telophase

Question 9

What happens during Prophase?

Answer 9

Chromatin condenses into chromosomes

Centrosomes move to opposite poles of the cell

Question 10

What happens during Prometaphase?

Answer 10

Nuclear membrane disintegrates

Spindle attaches to Chromatids

Question 11

What happens during Metaphase?

Answer 11

Chromatids line up at the equator of the cell

Question 12

What happens during Anaphase

Answer 12

Chromatids get separated and move to opposite poles of the cell

Question 13

What happens during Telophase

Answer 13

Nuclear envelope reforms

Chromosomes unfold into Chromatin

Question 14

Differences between Meiosis and Mitosis

Answer 14

Mitosis is in Somatic Cells, Meiosis is in Gametes
Meiosis has 2 cell divisions, Mitosis has 1
Mitosis creates 2 genetically identical daughter cells, Meiosis creates 4 genetically different daughter cells.

Question 15

When does Crossing Over occur

Answer 15

Prophase I

Question 16

How is genetic diversity produced in Meiosis

Answer 16

Independent Assortment

Crossing Over

Question 17

What is the process of maturation for a sperm cell (3)

Answer 17

Primordial Germ Cells -> Mitoses -> Spermatogonia

Question 18

Difference between Egg cell production and Sperm cell production

Answer 18

After Meiosis II for Sperm cell, 4 EQUAL gametes
After Meiosis II for Egg Cell, 1 Gamete and 3 Polar Bodies

Meiosis I occurs for egg cell pre birth of female, whereas meiosis initiates during puberty for male

Question 19

What is the process of maturation for an Egg cell

Answer 19

Primordial Germ Cells -> 30 Mitoses -> Oogonia

Question 20

What is non-disjunction

Answer 20

Failure of Chromosome pairs to separate during Meiosis I, or Sister Chromatids to separate during Meiosis II

Question 21

What is Gonadal Mosaicism

Answer 21

Occurs when precursor germline cells to Spermatazoa are a mixture of two or more cell lines

i.e one cell line is mutated and one is not - some sperm will have a mutation and others won’t (or eggs)

Question 22

Why does the risk of Gonadal Mosaicism increase with paternal age

Answer 22

Increasing time = Increasing chance of mutation

Question 23

Where is DNA found

Answer 23

Nucleus AND MITOCHONDRIA

Question 24

What are the stages of coiling in DNA?

Answer 24

Nucleosomes -> Supercoils -> Chromosomes

Question 25

Describe the process of DNA replication (5)

Answer 25

TOPOISOMERASE uncoils the DNA DNA Helicase breaks the H bonds between CBP, 2 strands are held apart SSb DNA polymerase lines up complimentary free nucleotides along the separated strands in an antiparallel 5' to 3' Leading Strand 5' -> 3' is synthesised in a continuous fashion Lagging strand 3' to 5' is synthesised in pieces called Okazaki fragments joined by DNA ligase

Question 26

Differences between RNA and DNA

Answer 26

``` DNA is double stranded DNA has a deoxyribose sugar RNA is single stranded RNA has a Ribose sugar RNA has U instead of a T ```

Question 27

By what process is mRNA made

Answer 27

Transcription

Question 28

What is rRNA used for

Answer 28

4 types of rRNA combine with each other to form 80s Ribosomes

Question 29

What is the function of tRNA

Answer 29

Carries an anti-codon complimentary to triplet codon, which is also attached to an Amino Acid

Question 30

4 features of DNA

Answer 30

Unambiguous - one codon for one AA, one AA has more than one codon Degenerate - 3 bases for a codon Non overlapping - Successive triplets read in order Universal

Question 31

What is an alternative version of a gene called

Answer 31

Allele

Question 32

What is a polymorphism

Answer 32

Variation in an allele from person to person

Question 33

Structure of a gene

Answer 33

Promoter region - switches the gene on Exons - coding regions of DNA Introns - non coding regions

Question 34

What is splicing

Answer 34

Removal of introns from pre-mRNA

Question 35

what is alternative splicing

Answer 35

Splice site varies - different proteins can therefore be made

Question 36

What is a splice site variant

Answer 36

The position along the base sequences at which splicing occurs changes

Question 37

What is a Non-Sense mutation

Answer 37

Codon is changed to a STOP CODON Caused by out of frame deletion

Question 38

Mis-Sense mutation?

Answer 38

Single base substitution which changes type of AA

Question 39

What is Allelic Heterogeneity?

Answer 39

Lots of different variations of one gene

Question 40

What is Locus Heterogeneity?

Answer 40

Variants in different gene give the same clinical conditions

Question 41

What is a mutation?

Answer 41

Damage to DNA sequence

Question 42

What are the causes of mutation

Answer 42

Environmental (Radiation, Chemical, Thermal) Spontaneous change

Question 43

Ways in which a dominant mutation effects normal function? (3)

Answer 43

1. ) Loss of Function - Changes in the amount of protein produced affect very sensitive pathways - stops working 2. ) Gain of Function - Increased protein production 3. ) Dominant Negative Mutations - Protein from mutant allele interferes with protein from normal allele

Question 44

Causes of disease (3)

Answer 44

Genetic Environmental Multifactorial ( most common)

Question 45

What is a Genomic disorder?

Answer 45

A condition that results from STRUCTURAL CHANGE to the genome, rather than DNA base change

Question 46

What is Lyonisation?

Answer 46

Only 1 of 2 allele active - therefore recessive alleles can be expressed even if heterozygous

Question 47

What are the categories of genetic disorder (4)

Answer 47

Chromosome Abnormality Single gene Polygene Multifactorial

Question 48

Common chromosome structural abnormalities (7)

Answer 48

Reciprocal - Transfer of Genetic material Robertsonian Translocation - Joining of 2 chromosomes Deletions - loss of part of a chromosome Insertions - 1 section of a chromosome is inserted into another Inversions - Segments of chromosome is reversed Ring Chromosomes - Breaks occur in arms of chromosomes, and so chromosomes bind Fragile site - Gap in chromosome which is likely to break

Question 49

What are the 2 types of mosaicism

Answer 49

Gonadal | Somatic

Question 50

What is somatic mosaicism

Answer 50

Genetic disorder confined to a part of the body, due to mutation in early development

Question 51

What is penetrance

Answer 51

% of individuals with a specific genotype showing the expected phenotype

Question 52

What is expressivity

Answer 52

Range of phenotypes expressed by a specific phenotype

Question 53

What is anticipation

Answer 53

Where genetic disorders affect successive generations earlier or more severely than expected

Question 54

What is the role of the nucleolus

Answer 54

Synthesise rRNA

Question 55

What are the two types of DNA found in a cell

Answer 55

Euchromatin | Heterochromatin

Question 56

If a cell is active it will contain what type of DNA

Answer 56

Euchromatin

Question 57

If a cell is inactive, it will contain what type of DNA

Answer 57

Heterochromatin - will stain dark