Genetics Flashcards
What does DNA stand for
Deoxyribonucleic acid
What are nucleotides
Phosphate
Deoxyribose sugar
Nitrogen rich bases
What is the shape of DNA
Double helix, like a twisted ladder: the uprights of the ladder are phosphate and sugar, and the rungs are bases
What are the four bases
Adenine
Thymine
Guanine
Cytosine
Describe complementary base pairing
The chemical structure of the rich bases means that they can only form chemical bonds with one of the other bases
A pairs with T
C pairs with G
Define allele
Different forms of the same gene
Define dominant
The characteristic that is a expressed in the heterozygous condition. To be observed in the appearance of the individual
Define genotype
Genetic information carried by an individual
Heterozygous
Having two different alleles on a homologous structure
Homozygous
Having two identical alleles on homozygous structure
Mutation
A mistake that happens as DNA is copied, causing a change to the base sequence
Phenotype
Observable characteristics of the individual
Pure breeding
Where all individuals have the same genetic information fir a chat geriatric generation after generation
Recessive
The characteristic that remains hidden in the heterozygous structure
Gene
A section of DNA that carries the genetic code for a particular characteristic
Autosomes
All the chromosomes in a cell other than the sex chromosomes
Centromere
The point on the chromosome, where two chromosomes are joined together
Chromatid
One of the strands of chromosomes following replication
Diploid number
The number of chromosomes in body cells: 2 sets
Haploid
The number of chromosomes in gametes: one set
Homologous structure
Chromosomes with genes for particular characteristics at the same location
Give 3 examples of facts about chromosomes
Long thin thread like structured, found in the nucleus of the cell
Chromosomes are made of DNA and protein
Steps in genetic manipulation (7)
- Plasmids are removed from a bacterium
- Plasmids are cut using an enzyme (restriction enzyme)
- DNA is removed from human cells
- DNA is cut using an enzyme to isolate the gene
- Human gene is inserted into the plasmid to form recombinant DNA
- The recombinant DNA is put into a bacterium
- Bacterial cells grow and divide to produce many copies of the introduced gene
How many cells in the human body
46 chromosomes (in 23 pairs)
How many chromosomes in gametes
23 chromosomes, one in each pair
Plasmids
Ring if DNA found in bacteria
What did Mendel test his experiments with
Pea plants
What is the purpose of Punnett squares
To determine and predict specific characteristics of an offspring when two parents mix
Sex linked inheritance
There are some conditions, eg colourblindness, that are sex inherited. This means the genes involved are on sex determining chromosomes.
Chromosomes for a female
XX
Chromosomes for male
XY
Steps of meiosis (6)
- Pairs of double stranded chromosomes line up
2. One double stranded chromos
Describe mitosis
Mitosis produces two daughter cells that are identical to the parent cell. This type of cell division is involved in growth and repair of the body.
Describe meiosis
Mitosis produces gametes (eggs and sperm) that have half the number of chromosomes as the parent cell
Steps of mitosis, include PMAT
Prophase: chromosomes are replicated to become double stranded, and then they become visible.
Metaphase: double stranded chromosomes line up along the equator (middle) of the cell
Anaphase: the chromosomes move to oppose ends of the cell
Telophase: two nuclei form, each with the diploid number of chromosomes. The membranes also form separating the nuclei into two daughter cells
Steps of meiosis, include PMAT
Prophase 1: chromosomes line up with homologous pairs
Metaphase 1: pairs of double stranded chromosomes line up
Anaphase 1: one double stranded chromosomes of each pair moves to each pole
Telophase 1: two cells are formed
Prophase 2:
Metaphase 2: double stranded chromosomes line up
Anaphase 2: chromatids separate and move to poles
Telophase 2: four cells result with a haploid number of chromosomes
