Human Genetics Flashcards
What is genetics?
the biological study of hereditary, attempting to predict the characteristics of offspring from mating
Name the 2 processes of cellular reproduction
meiosis
mitosis
Which process is used in the reproduction of sex cells (ova/egg and sperm(?
meiosis
Which process is used in the reproduction of eukaryotic cells?
mitosis
Describe the process of mitosis
a cell doubles its DNA, then splits into 2 identical daughter cells, each with 46 chromosomes (23 pairs)
Describe the process of meisos
a cell duplicates its DNA, then splits into 4 non-identical daughter cells, each with 23 chromosomes
What term means a cell has 23 chromosomes (half the amount of a eukaryoctic cell)
haploid
Which term means a cell has 46 chromosomes?
diploid
How many chromosomes does a diploid cell have?
46
How many chromosomes does a haploid cell have?
23
What name is given to the reproduction of sex cells such as ova and sperm?
meiosis
What is a gene?
a unit of hereditary on a pair of chromosomes
What is an allele?
half a gene, or the location of a characteristic on 1 chromosome
What does homozygous mean?
having two dominant or recessive alleles (both are the same)
What does heterozygous mean?
having 1 dominant and 1 recessive allele (one of each)
What does dominat mean?
if a dominant allele is present it displays the characteristic in the individual
What does reessive mean
that you need to have 2 of the same alleles to show the characteristic
Which term means that you have 2 of the same alleles?
homozygous
Which term means that you have 1 of each allele?
heterozygous
What is a punnet square?
a diagram used to determine the probability of an offspring haing a particular genotype
What is a phenotype?
the outward display of a characteristic (what you see)
What is a genotype?
the individual’s make up of genes
What is a gamete?
a sex cell (sperm or ova/egg)
What is a zygote?
the cell produced when a sperm has fertilised an ovum (egg) which contains 1/2 it’s DNA from each - it has 46 chromosomes
Is Cystic Fibrosis a dominant or recessive gene?
recessive
Is Phenylketonuria a dominant or recessive gene?
recessive
Is Sickle Cell Disease a dominant or recessive gene?
partially dominant
Is Huntington’s Disease a dominant or recessive gene?
dominant
What is Phenylketonuria?
where the body is unable to break down the amino acid phenylalanine, which builds up, leading to brain damage
What is sickle cell disease?
where red blood cells develop abnormally, so they can block blood vessels, resulting in tissue and organ damage
What is cystic fibrosis?
where your lungs and digestive system become clogged with thick, sticky mucous, causing respiratory infections
What is Huntington’s Disease?
a condition which damage nerve cells in the brain, affecting movement, cognition, balance, awareness, judgement and mood
What’s the probability of a child being born to 2 parents with phenylketonuria, having it?
100%
As its a recessive gene, both parents would be pp, so all children would be pp
What’s the probability of a child being born to 1 homozygous PKU, and 1 heterozygous non-PKU parent?
(draw the punnet square to help you)
50% PKU
50% - unaffected carrier
What are the possible genotypes of a person without PKU?
PP - homozygous non-PKU
Pp - heterozxygous non-PKU (these are carriers)
What’s the probability of a child having PKU if they are born to 2 homozygous parents, 1 PKU, 1 non-PKU,
100% non-PKU (carriers)
What’s the probability of a child having Huntington’s Disease if they are born to 2 heterozygous Huntington’s parents
75% Huntington’s
25% - HH
50% - Hh
25% - hh
What’s the probability of a child having Huntington’s Disease if they are born to a homozygous Huntington’s and homozygous non-Huntington’s parents?
100% Huntington’s
all Hh
If someone is heterozygous for Sickle Cell disease, what does that mean?
They have sickle cell trait (which means they’re 50% likely to get the symptoms of sickle cell disease)
Which genetic disease is carried on a dominant gene?
Huntington’s disease
Which genetic diseases are carried on recessive genes?
Cystic Fibrosis
Phenylketonuria
Which genetic disease is partially dominant?
Sickle cell disease
Identify 2 diagnostic tests that can be used to test if a foetus will be born with certain genetic diseases?
amniocentesis
chorionic villus sampling
Describe amniocentesis
a long, thin needle is inserted through your abdominal wall, guided by an ultrasound image. A small sample of amniotic fluid is removed for analysis.
Describe Chorionic Villus Sampling
a tube or small forceps are inserted through the cervix and a small sample of cells is removed from the placenta
