L-3 Genetics, Environment & Disease Flashcards
where is DNA found?
what does DNA contain?
-its a code in the nucleus of our cells
-contain a set of instructions to make us who we are
why does the brain and heart behave differently ?
brain cells obeys a part of the instructions in DNA and heart cells obeys another set
Genome
-The genetic information particular to a given organism
-Same genome in every cell of an individual
What’s the region for coding protein in the DNA called ?
GENES
What’s genes
The regions coding for proteins in DNA
what’s contained in the chromosome
-Each chromosome has one long DNA molecule with hundreds or thousands of genes
what’s a somatic cell
any cell other than a gamete
how many chromosomes does human have
23 pairs of chromosome
what are the two chromosomes in each pair called
homologous
autosomes
22 pairs of chromosomes and one pair of sex chromosomes which determine the sex of the individual
what’s karyotype
its the order display/pattern of the pairs of chromosomes from a cell
3 classes of genetic disease
- chromosomal disorder
- monogenic disorder (single gene defects)
- polygenic disorder (multi-gene defects)
what’s nondisjunction (chromosome disorder)
the homologous chromosomes during meiosis leads to one gamete receiving two of the same type of chromosome and another gamete receiving none
what’s aneuploidy (chromosome disorder)
results of fertilising the gametes with nondisjunction- offspring have an abnormal number of a particular chromosome
chromosome disorder
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
monosomic
a zygote that has only one copy of a particular chromosome
trisomic
a zygote has three copies of a particular chromosome
Down syndrome (Trisomy 21)
what is it ?
what is it an example of ?
- Its an aneuploid condition where there is three copies of chromosome 21
-example of chromosome disorder
Aneuploidy of sex chromosomes conditions
-kinefelter syndrome results extra chromosome in male producing XXY
-monosomy X called Turner syndrome produces X0 females whole are infertile
classification of monogenic disorder (single gene)
-autosomal dominant
-autosomal recessive
-X-linked
genes come in pairs called
Diploid
two copies of each gene is called
alleles they can be identical or different
what determines our physical traits
DNA
Example of Autosomal Dominant disorders
Achondroplasia (dwarfism)
one mutated copy of the gene is sufficient for a person to be affected
Example of Autosomal Recessive Disorder
cause?
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
what’s albinism
a recessive condition
characterised by a lack of pigmentation in
skin and hair
Cystic Fibrosis
what is it ?
symptoms?
may face ?
-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
sickle cell
what is it? (heterozygotes and homozygous)
symptoms ? (heterozygotes and homozygous)
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
homozygous
same two copies of genes same allele
heterozygous
two different alleles
X-linked disorder
what is it?
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
example of X-linked disorder
Duchenne muscular dystrophy
-involves rapidly worsening muscle weakness
-in males symptoms show before age 5
