DNA and inheritance Flashcards
Where is DNA found?
The nucleus of a cell.
What are the 6 key points regarding DNA?
- DNA forms a chemical code which acts as instructions for the cell to make proteins.
- The make-up of the DNA molecule varies in different individuals, although it is made up of the same basic components.
- All living processes are a series of chemical reactions in cells.
- All these reactions are are controlled by enzymes.
- All enzymes are proteins.
- The chemical reactions that a cell can carry out are therefore determined by the makeup of the DNA in that individual.
What is DNA made up of?
DNA is made up of 2 long chains of alternating sugar and phosphate molecules connected by pairs of bases.
What is the shape of DNA?
The ladder like structure are twisted to form a double helix shape.
What are the 4 bases of DNA?
Adenine (A) and thymine (T), guanine (G) and cytosine (C).
What do bases do?
Bases form the instructions, in a code, for the manufacture of proteins. It determines which amino acids are used to make a given protein and in what order.
What is the ‘code’?
The ‘code’ consists of triplets of bases along the DNA. Each triplet codes for an individual amino acid in the protein.
What is in the nucleus of a cell?
The long DNA molecules are coiled up into structures called chromosomes. DNA is the raw material of genes - a gene is a short length of DNA that codes for 1 protein.
What is genetic profiling?
You can look at the bases in a DNA molecule and see to what extent different DNA samples are similar. This analysis produces a genetic profile. The genetic profiling process can be used to show the similiarity between 2 different samples.
What are the uses of genetic profiling?
- Criminals can be positively identified if DNA samples from the crime scene match theirs.
- If there is a dispute as to who is the father of a child, the father DNA will have many similarities to the child’s.
- The DNA of a species can be compared with each other to establish how closely related they are. The more closely related, the more similar the DNA.
- Genetic profiling can detect certain genes that may be associated with a particular disease. This opens up the possibilities of treatment.
What are the steps of carrying out genetic profiling?
1 - a sample of the cells is collected (e.g blood or skin). These cells are broken up and the DNA extracted.
2 - the DNA is ‘cut up’ by enzymes so that it ends up in fragments of different sizes.
3 - the fragments are then separated, a pattern develops, which is the genetic profile.
What is a gene?
A length of DNA that codes for one protein.
What is an allele?
A variety of a gene.
What is a chromosome?
A length of DNA that contains many genes, found in the nucleus and is visible in cell division.
What is a genotype?
The genetic make-up of an individual (cc, CC, Cc).
What is phenotype?
The description of the way the genotype shows itself (blue eyes, brown hair, short/tall).
What is meant by dominant?
An allele that shows in the phenotype whenever it is present (shown by an uppercase letter).
What is meant by recessive?
An allele that is hidden when when a dominant allele is present (shown by a lower case letter).
What is meant by F1/F2?
Short for first generation and second generation in a genetic cross (in plants).
What is homozygous/homozygote?
A homozygote contains 2 identical alleles for the gene concerned - it is homozygous.
What is heterozygous/heterozygote?
A heterozygote contains 2 different alleles for the gene concerned - it is heterozygous.
What is ‘selfing’?
A technique by which pollen from a plant is used to fertilise ovules in the flowers of the same plant.
What are the 4 basic rules of inheritance?
- There are copies of each gene in the body, one coming from each parent.
- The gametes contain one copy of each gene.
- The copies are not necessarily the same, as every gene has different versions called alleles.
- Individuals may have 2 of the same alleles for a particular gene (homozygous) or 2 different alleles (heterzygous).
What is monohybrid inheritance?
Monohybrid inheritance is the name given to the inheritance of one gene.