heredity Flashcards
where is DNA located in the cell?
the nucleus
how is DNA organised in the nucleus?
organised into units called genes, genes are found in chromosomes
what is a gene?
a segment of DNA that codes for a particular protein
how many pairs of chromosomes do humans have?
23 (46 total)
what does diploid mean?
a paired set of chromosomes in somatic cells
what is a somatic cell?
cells of the body except sex cells
what are gametes?
sperm and egg cells
what does haploid mean?
the possession of each chromosome in a cell
what sex chromosomes does a female have?
xx
what sex chromosomes does a male have?
xy
what is an autosome?
any chromosome not involved in sex determination
what is a sex chromosome?
the chromosomes that determine your sex (gender)
what are the components of a nucleotide?
phosphate, sugar, nitrogenous bases
what are the building blocks of DNA?
nucleotides
What components form the DNA backbone?
sugar and phosphate
what components form the rungs?
the nitrogenous bases
what are the four types of bases>
adenine, thymine, cytosine, guanine
what is complementary badge pairing?
bases bending with one another
what is a karyotype?
a karyotype is the visualisation of an individuals collection of chromosomes
what is the purpose of a karyotype?
to look at abnormal structures or numbers of chromosomes
what is a homologous chromosome?
the same size, and shape and carry the same genes
where do you get the matching pairs?
one from your mum and the other from your dad
what is an allele?
the different forms of a gene
what is the difference between a gene and an allele?
gene specifies traits, alleles specify the form the gene takes
what are dominant alleles?
will always be expressed when they’re present
what are recessive alleles?
only express when there are two recessive ones
what is a phenotype?
the trait that is seen
what is homozygous?
the same alleles
what is heterozygous?
different alleles
what is a genetic cross?
measures the probability for a certain genetic cross
what is a punnet square?
the tool we use to do a cross
how to complete a punnet square?
- Designate characters to represent alleles.
- Write the genotype and phenotype of the parents.
- Use a grid to work out genetic combinations.
- Write the genotype and phenotype ratios of offspring.
