DNA DNA is the molecule that is in charge of storing genetic information.

DNA DNA is the molecule that is in charge of storing genetic information. It’s like the English language except that there are only 4 letters (A,T,C,G) and all the words are 3 letters long.

DNA DNA is the molecule that is in charge of storing genetic information. It’s like the English language except that there are only 4 letters (A,T,C,G) and all the words are 3 letters long. A single section of DNA would contain those letters (nucleotides) in some sequence. If this section is in ‘charge’ of something we call it a gene……

GENE Gene – a section of DNA in charge of something.

GENE Gene – a section of DNA in charge of something. Could be in charge of making a protein (like the gene for the molecule keratin has its nucleotides in an order such that the amino acid sequence that is made from those directions will make keratin)

GENE Gene – a section of DNA in charge of something. Could be in charge of making a protein (like the gene for the molecule keratin has its nucleotides in an order such that the amino acid sequence that is made from those directions will make keratin) Could be a ‘regulatory’ gene – like a foreman in a factory who produces nothing directly, but who receives directions and then directs others to influence what gets made. Easier to think of the former – one gene, one protein.

CHROMOSOMES The total DNA of an organism (its genome) is small enough in bacteria that it can all be on a single molecule. It’s a single circular chromosome.

CHROMOSOMES The total DNA of an organism (its genome) is small enough in bacteria that it can all be on a single molecule. It’s a single circular chromosome. But in us complex creatures, there’s way too much to fit on one chromosome. So it’s packaged in ‘volumes’.

CHROMOSOMES The total DNA of an organism (its genome) is small enough in bacteria that it can all be on a single molecule. It’s a single circular chromosome. But in us complex creatures, there’s way too much to fit on one chromosome. So it’s packaged in ‘volumes’. Every organism has a ‘characteristic’ # of chromosomes. Fruit flies have 8. Plants have many dozens, even hundreds. We humans have 46.

SOOOOO… A chromosome consists of a long stretch of DNA, portions of which are ‘genes’. So, we could say that a chromosome consists of a bunch of genes.

SOOOOO… A chromosome consists of a long stretch of DNA, portions of which are ‘genes’. So, we could say that each chromosome consists of a bunch of genes. These genes are NOT organized by function. For example, there is a set of genes that collectively are in charge of cell division. But they aren’t located together – they’re spread out amongst all the chromosomes.

ALSO! Remember that each of us complex critters have a set of genetic material from mom and another from dad.

So you have a pair of each of 23 chromosomes

Remember that each of us complex critters have a set of genetic material from mom and another from dad. So you have a pair of each of 23 chromosomes Each pair is homologous in that they have the same genes – they’re in charge of the same stuff.

GENE RELATIONSHIPS What this means is that the homologous genes might not say the same thing for example, the earlobe gene might say ‘attached’ or might say ‘free’.

GENE RELATIONSHIPS What this means is that the homologous genes might not say the same thing for example, the earlobe gene might say ‘attached’ or might say ‘free’. If they do say the same thing there’s no argument between the genes. This is ‘homozygous’.

GENE RELATIONSHIPS But if they’re different they’ll need to find way to resolve that difference.

GENE RELATIONSHIPS But if they’re different they’ll need to find way to resolve that difference. A different form for a particular gene is called an ‘allele’.

GENE RELATIONSHIPS But if they’re different they’ll need to find way to resolve that difference. A different form for a particular gene is called an ‘allele’. Mendel’s pea plant alleles all had a particular kind of relationship.

GENE RELATIONSHIPS But if they’re different they’ll need to find way to resolve that difference. A different form for a particular gene is called an ‘allele’. Mendel’s pea plant alleles all had a particular kind of relationship.

GENE RELATIONSHIPS If they were both present (one from mom, one from dad, called ‘heterozygous’) only one was ‘expressed’.

OTHER VOCABULARY Trait – a physical characteristic

OTHER VOCABULARY Trait – a physical characteristic Genotype – the actual genetic makeup of the organism (homozygous dominant, heterozygous, homozygous recessive) for a particular trait

OTHER VOCABULARY Trait – a physical characteristic Genotype – the actual genetic makeup of the organism (homozygous dominant, heterozygous, homozygous recessive) for a particular trait Phenotype – what it looks like – for that trait.

OTHER VOCABULARY Trait – a physical characteristic Genotype – the actual genetic makeup of the organism (homozygous dominant, heterozygous, homozygous recessive) for a particular trait Phenotype – what it looks like – for that trait. Locus – where the gene is located

OTHER VOCABULARY Gamete – a sperm or egg – has one set of chromosomes.

OTHER VOCABULARY Gamete – a sperm or egg – has one set of chromosomes. Haploid – refers to any cell with only one set of chromosomes – like gametes!

OTHER VOCABULARY Gamete – a sperm or egg – has one set of chromosomes. Haploid – refers to any cell with only one set of chromosomes – like gametes! Zygote – the product of two gametes coming together in fertilization

OTHER VOCABULARY Gamete – a sperm or egg – has one set of chromosomes. Haploid – refers to any cell with only one set of chromosomes – like gametes! Zygote – the product of two gametes coming together in fertilization Diploid – any cell with two sets of chromosomes – most of our cells are