L-3 Genetics, Environment & Disease

Question 1

where is DNA found?
what does DNA contain?

Answer 1

-its a code in the nucleus of our cells
-contain a set of instructions to make us who we are

Question 2

why does the brain and heart behave differently ?

Answer 2

brain cells obeys a part of the instructions in DNA and heart cells obeys another set

Question 3

Genome

Answer 3

-The genetic information particular to a given organism
-Same genome in every cell of an individual

Question 4

What’s the region for coding protein in the DNA called ?

Answer 4

GENES

Question 5

What’s genes

Answer 5

The regions coding for proteins in DNA

Question 6

what’s contained in the chromosome

Answer 6

-Each chromosome has one long DNA molecule with hundreds or thousands of genes

Question 7

what’s a somatic cell

Answer 7

any cell other than a gamete

Question 8

how many chromosomes does human have

Answer 8

23 pairs of chromosome

Question 9

what are the two chromosomes in each pair called

Answer 9

homologous

Question 10

autosomes

Answer 10

22 pairs of chromosomes and one pair of sex chromosomes which determine the sex of the individual

Question 11

what’s karyotype

Answer 11

its the order display/pattern of the pairs of chromosomes from a cell

Question 12

3 classes of genetic disease

Answer 12

1. chromosomal disorder
2. monogenic disorder (single gene defects)
3. polygenic disorder (multi-gene defects)

Question 13

what’s nondisjunction (chromosome disorder)

Answer 13

the homologous chromosomes during meiosis leads to one gamete receiving two of the same type of chromosome and another gamete receiving none

Question 14

what’s aneuploidy (chromosome disorder)

Answer 14

results of fertilising the gametes with nondisjunction- offspring have an abnormal number of a particular chromosome

Question 15

chromosome disorder

Answer 15

chromosome alteration in humans and other mammals often lead to miscarriage or cause development of disorders
1. gain or loss of a complete chromosome
2. deletion or insertion of part of a chromosome
-plants can tolerate genetic changes better

Question 16

monosomic

Answer 16

a zygote that has only one copy of a particular chromosome

Question 17

trisomic

Answer 17

a zygote has three copies of a particular chromosome

Question 18

Down syndrome (Trisomy 21)
what is it ?
what is it an example of ?

Answer 18

• Its an aneuploid condition where there is three copies of chromosome 21
  -example of chromosome disorder

Question 19

Aneuploidy of sex chromosomes conditions

Answer 19

-kinefelter syndrome results extra chromosome in male producing XXY
-monosomy X called Turner syndrome produces X0 females whole are infertile

Question 20

classification of monogenic disorder (single gene)

Answer 20

-autosomal dominant
-autosomal recessive
-X-linked

Question 21

genes come in pairs called

Answer 21

Diploid

Question 22

two copies of each gene is called

Answer 22

alleles they can be identical or different

Question 23

what determines our physical traits

Answer 23

DNA

Question 24

Example of Autosomal Dominant disorders

Answer 24

Achondroplasia (dwarfism)
one mutated copy of the gene is sufficient for a person to be affected

Question 25

Example of Autosomal Recessive Disorder
cause?

Answer 25

Albinism, Cystic fibrosis & Sickle cell anaemia
both parents carry one normal allele and one mutated
two copies of genes need to be mutated for a person to be affected

Question 26

what’s albinism

Answer 26

a recessive condition
characterised by a lack of pigmentation in
skin and hair

Question 27

Cystic Fibrosis
what is it ?
symptoms?
may face ?

Answer 27

-primarily affects the lungs and digestive system
-cystic fibrosis allele results in defective or absent chloride channels in plasma membrane that lead to chloride ions building up outside cell
-symptoms : thick sticky mucus build up blocks bronchial tube and prevents absorption of nutrients in small intestine
-open to chest infection and malnutrition

Question 28

sickle cell
what is it? (heterozygotes and homozygous)
symptoms ? (heterozygotes and homozygous)

Answer 28

homozygous- all haemoglobin is abnormal (sickle-cell)
leads to physical weakness, pain, organ damage, paralysis
heterozygotes- usually healthy but suffer some symptoms they are less susceptible to malaria parasite

Question 29

homozygous

Answer 29

same two copies of genes same allele

Question 30

heterozygous

Answer 30

two different alleles

Question 31

X-linked disorder
what is it?

Answer 31

mutated gene found on the X chromosome
males more likely to suffer
sons of females who are carries to the disease have 50% chance of having the disease. daughters have 50% of being carriers

Question 32

example of X-linked disorder

Answer 32

Duchenne muscular dystrophy
-involves rapidly worsening muscle weakness
-in males symptoms show before age 5