Genetics

Question 1

Describe the human genome?

Answer 1

the complete set of nuclei acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule food within individual mitochondria

Question 2

Define chromosome

Answer 2

a thread-like structure of nuclei acids and protein found in the nucleus of most living cells, carrying genetic information in the forms of genes

Question 3

Define locus

Answer 3

the position of a gene along the chromosome

Question 4

Define gene

Answer 4

a length of DNA encoding the information to make a protein

Question 5

Define DNA

Answer 5

a self-replicating material which is present in nearly all living organisms as the main constituent of chromosomes - it is the carrier of genetic information

Question 6

Explain the structure of chromosome

Answer 6

• each is a single molecule of DNA, tightly packaged by proteins with genres located at positions along the chromosome in a linear sequence

Question 7

Describe the position of genes along the chromosomes

Answer 7

located at positions along the chromosome in a linear sequence

Question 8

What are homologous chromosomes?

Answer 8

in our body cells each chromosome is paired i.e. forms a homologous pair - one paternal and one maternal - homologous chromosomes contain the same genes

Question 9

What is a human karyotype?

Answer 9

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species

Question 10

What is the word for chromosome 1-22?

Answer 10

autosomes

Question 11

What are X and Y chromosomes?

Answer 11

sex chromosomes

Question 12

What are the female chromosomes?

Answer 12

XX

Question 13

What are the male chromosomes?

Answer 13

XY

Question 14

Define alleles

Answer 14

an allele is a version of a gene - X and Y have two alleles

Question 15

Define ploidy

Answer 15

the number of sets of chromosomes in each cell

Question 16

Define haploid

Answer 16

one set of chromosomes

Question 17

Define diploid

Answer 17

two sets of chromosomes

Question 18

Define mitosis

Answer 18

normal cell division, creating two genetically-identical daughter cells

Question 19

Define meiosis

Answer 19

reduction division in which each daughter cell receives one cope of each chromosomes

Question 20

Briefly explain the human life cycle

Answer 20

• egg and sperm cells (haploid n=23)
• ^ carry one copy of each chromosomes in their nucleus
• at fertilisation, the egg and sperm cell nuclei fuse
• the zygote (fertilised egg) therefore is diploid (2n=46)
• ^ mean it has a copy of each haploid chromosome

Question 21

What percentage of 1st trimester miscarriages are caused by chromosomal abnormalities?

Answer 21

50%

Question 22

What is a change in the number of chromosomes usually caused by?

Answer 22

usually an isolated occurrence

Question 23

What is a change in the structure of chromosomes usually caused by?

Answer 23

translocations, may be inherited

Question 24

How many newborns in 200 have multiple congenital abnormalities?

Answer 24

1

Question 25

What chromosomal abnormality is trisomy 13?

Answer 25

patau’s syndrome

Question 26

What chromosomal abnormality is trisomy 18?

Answer 26

edward’s syndrome

Question 27

What chromosomal abnormality is trisomy 21?

Answer 27

down’s syndrome

Question 28

Chromosomal abnormalities are reliant on base-pairing rules. What are the pairs?

Answer 28

A-T

G-C

Question 29

What is DNA replication?

Answer 29

the copying of genetic material whereby the two strands ‘unzip’ and rejoin using base-pairing rules in 2 identical DNA strands

Question 30

During the ‘flow of genetic info’ otherwise known as transcription and translation, what occurs?

Answer 30

DNA which is made up of A, T, G, C are unziped to be RNA. mRNA goes in, makes a copy of the DNA where amino acids are created in order to make proteins

Question 31

What input do proteins have in the human genome?

Answer 31

genes are used to direct the synthesis of proteins in the cells. the proteins take part in our development from the egg to the adult

Question 32

Explain where variation in human genome occur?

Answer 32

variation in the sequence of the genes contribute to variations between individuals and some inherited genetic variants lead to genetic diseases e.g. cystic fibrosis