Genetics Flashcards
Where is genetic material found and what is it?
Genetic material is found in the nucleus of a cell and is composed of a polymer called DNA (contained in structures called chromosomes)
What is DNA made up of?
DNA is made of two strands, forming a double helix (polymer)
What is a gene?
A small section of DNA on a chromosome, which codes for particular sequence of amino acids to make a specific protein.
What is a genome?
The genome of an organism is all of its genetic material
How will the study of human genome help medicine?
- It will help with a search for genes linked to different diseases
- It will help our understanding and treatment of inherited diseases
- It will help the tracing of human migration patterns from the past.
What is DNA?
DNA is a polymer of repeating nucleotide units
What are the four different nucleotides?
Each nucleotide consists of a common sugar and phosphate group however, they have one of four different bases (A, T, C, G)
What is DNA comprised of?
Two complimentary strand of nucleotides.
Which bases align with which?
A C base will link with a G base.
A T base will link with an A base.
What is DNA for?
DNA codes for proteins. The order of bases in the DNA controls the order in which amino acids are assembled to produce a particular protein. Three bases form the code for one amino acid.
How are proteins made?
Proteins are synthesised on ribosomes. mRNA is a molecule which takes the DNA code from the nucleus to the ribosomes. Carrier molecules, then bring amino acids in a specific order to the ribosome so a specific protein can be made.
What happens when a protein is complete?
Protein is folded to form a unique shape, which allows the protein to do their job as enzymes, hormones, or structure, forming proteins (e.g. Collagen.)
What is a mutation?
A change in a piece of DNA’s sequence of bases. This alter the sequence of amino acids in the protein the DNA codes for.
What is important to remember about mutations?
Mutations occur continuously, and most do not affect the appearance of the protein or its function
What happens if the protein shape is altered?
- A substrate no longer fits the enzymes active site
- A structural protein loses its strength
What happens when mutations are in non-coding parts of DNA?
It may affect how genes are expressed
What is a gamete?
A sex cell
What is a chromosome?
Long strands of DNA found in a nucleus
What is a gene?
A section of DNA, which codes for a protein
What is an allele?
A form of a gene
What is meant by dominant?
The allele which controls the development of a characteristic, even when only present on one chromosome
What is meant by recessive?
The allele which controls the development of a characteristic only when dominant allele is not present in either chromosome.
What is a homozygous?
A genotype when the alleles are the same
What is a heterozygous?
A genotype when the alleles are different
What is the genotype?
The types of alleles an organism contains
What is the phenotype?
The characteristics resulting from the genotype
What causes genetic disorders?
Faulty genes
How are genetic disorders passed?
They are inherited
What is polydactyly?
Polydactyly is a genetic disorder caused by dominant allele. Sufferers have extra fingers or toes. Because it is dominant, the allele needs only to be inherited from one parent.
What is cystic fibrosis?
Cystic fibrosis is a genetic disorder caused by a recessive allele. Sufferers cell membranes produce too much mucus. Because it is caused by a recessive allele:
- It must be inherited from both parents
- You can carry the allele without having the disorder
- Two parents without disease can have a child with the disorder
What can be done to help reduce the prevalence of genetic disorders?
Embryonic screening for alleles
What are the concerns with embryonic screening?
- People are against the destruction of rejected embryos (abortion)
- Expensive to screen
- Screening poses a risk to embryo and mother
- Can cause prejudice against those with disorders
What are the benefits of embryonic screening?
- Stops people struggling with different disorders
- Reduces health-care costs
- Baby with condition can be expensive and costs into further life
- Rejected embryos can be used in stem cell treatment
What happened in the mid-19 century to do with inheritance?
Gregory Mendel carried out breeding experiments on pea plants and observed the inheritance of characteristics is determined by ‘units’ that are passed on to descendants unchanged.
Why were Mendel’s ideas not accepted?
- Chromosomes, DNA and genes were not known about
- He wasn’t a respected scientist (only a monk)
- Many scientists were unaware of his work
What happened in the late 19th century to do with inheritance?
Behaviour of chromosomes during cell division was observed
What happened in the early 20th century to do with inheritance?
It was observed that chromosomes and Mendel’s ‘units’ behaved in similar ways. This led to the idea that Mendel’s ‘units’ were located on chromosomes.
What happened in the mid-20 century to do with inheritance?
The structure of DNA was determined and the mechanism of gene function was worked out
What is important to know about characteristics?
Some phenotypes are controlled by a single gene (red green colour blindness). However, most are a result of multiple genes.
What determines the gender of a baby?
One of the pairs of chromosomes has the genes that determine sex. In females, the sex chromosomes are the same (XX) and in males, they are different (XY)
How do we know if the disease is caused by a dominant allele?
If both parents suffer from the disease and they have a child that is not a sufferer, then the disease must be caused by dominant allele
How do you know if the disease is caused by a recessive allele?
If both parents do not suffer from the disease and I have a child that is a sufferer and the disease is caused by recessive allele and both of the parents are carriers
What is a carrier?
Carriers have an allele for disease, but don’t actually have the disease themselves. You can only be a carrier for disease if it is caused by recessive allele.
