study of the biological mechanisms by which an organism's traits are passed from generation to generation
ballpark number of genes
20 to 30,000
how many genes are enough to have unique human beings
33 with 2 settings: on or off (2³³ = 8.6bn)
names for people for nature and those for nurture
nativists and empiricists
Matt Ridley argument about nature/nurture debate
genes respond to environment e.g. they switch each other on and off
Sequence (1): Genetic Material
gives instructions on growth pattern/function for a cell. Resides in nucleus of most cells (viruses, which do not have cells are made up almost entirely of genetic material)
(2) each cell contains
46 chromosomes, which are paired into 23 pairs of homologous (similar) chromosomes, of which 1 pair are the sex chromosomes
(3) Gene: define
are portions of the molecule DNA, many of which contain instructions to make proteins
(4) DNA stands for..., is a .... which is ... long!
DeoxyriboNucleic Acid... molecule... almost 2 metres
(5) DNA is composed 2... made up of ..., ... and 4 different ..., which are ..., ..., ... and...
strands of nucleotides
sugar, phosphate and bases
Adenine, Thymine, Cytosine, Guanine
Examples of proteins
Antibodies - are specialized proteins involved in defending the body from antigens (foreign invaders)
Enzymes - are proteins that facilitate biochemical reactions. They are often referred to as catalysts because they speed up chemical reactions.
what percentage of DNA in your chromosomes do you share with chimps? with other humans?
A proteins is a chain of ...
Genome is an ... ... ... ... ... and is composed of ... base pairs
entire set of 23 chromosomes
Single Nucleotide Polymorphism. When genome is copied to make another cell, a base can be left out/substituted/added to. A substitution creates a SNP. These SNPs account for many of the differences between humans
How many SNPs are there>
why are there 2 sets of 23 chromosomes?
you inherit each set from each of your parents
How do you inherit your sex?
you inherit 1 of the 2 X chromosomes of your mother and either X or Y from your father
male chromosome pair / female chromosome pair
XY / XX
which cells have only 1 set of 23 chromosomes
egg cells and sperm cells (together called gametes), which implies that you only get half your genes from your mother and half from your father
the 23 chromosomes out of the total of 46 are chosen at random to go into fertilised egg, which implies that...
you are different from your brother
set of traits resulting from interaction of genes and environment
How are proteins made from DNA
DNA code has to be transferred to another type of nucleic acid, RNA or RiboNucleic Acid. RNA transports the code from DNA to the protein-making parts of the cell
process of cell dividing in 2, whereby chromosomes duplicate
creation of cell with only 23 chromosomes (rather than 46)
(1) first meiotic division: chromosomes duplicate and then homologous chromosomes pair up randomly. then cell divides into diploid cells (cells containing 46 chromosomes)
(2) second meiotic division: diploid cells divide into haploid cells (containing 23 chromosomes), thus creating 4 gametes
centre of a chromosome (point at middle of X formed by chromosome)
e.g. blood type
is one of 2 or more forms of a gene
e.g. at locus for blood type gene, there are 3 alleles (I^A, I^B and I^O). Because there are pairs of homologous chromosomes, there are 6 possible combinations, or GENOTYPES, of these alleles (AA, AB, AO, BB, BO, OO). These 4 possible PHENOTYPES (BB/BO > B type; AA/AO > A type; AB; and O)
two alleles at a locus can be described as .... or .... [Define]
dominant or recessive.
Where the heterozygote is indistinguishable from one of the homozygotes, the allele involved is said to be dominant to the other, which is said to be recessive to the former