Download 2012 Genetics Vocab and Notes

Genetics Vocabulary and Notes – 2012
Starting with some reminders from section 8.3 (p.236) and 3.2 (p.73)
Genetics - The study of how organisms inherit their characteristics from their parents.
Basically how do the genes we inherit in our DNA, provide all of the instructions and
programming needed, to build and run a living being.
Genetics studies how a simple chemical like DNA could – through the power of living
beings, nature, and huge amounts of time, with the help of natural selection and
evolution, produce all of the different plants, animals, fungi, and microscopic life
seen on Earth.
Genetics also studies how the instructions written in our DNA help decide what we look
and act like, what we are good or bad at, what diseases or cancers we might get, and
more.
Genetics studies patterns of inheritance, for instance, how can my grandparents, parents,
sisters and brothers all have brown eyes and I have blue eyes?
In the last 20 years, genetics has been increasingly studied as part of health care and
fertility treatment. Genetic research shows real promise for new treatments of
some cancers and genetic diseases. There is also promise for treating some of the
diseases of old age.
Written in the letter pairs A-T and G-C of the DNA language of life are:
1.) Instructions for the machines inside the cell that make a perfect copy of the DNA
strand to put into every living cell.
2.) The instructions for making RNA copies of the DNA genes, and for using that RNA plus amino acids, tRNA, and organelles like ribosomes, endoplasmic reticulum and
golgi bodies used to build proteins.
3.) Controller and modifier genes, that give grammar to the DNA language of life.
This grammar has all the tools needed to turn on and off different genes and sets of
genes in the right combinations and at the right time to make an eagle from an egg
and let it live its life and make more babies.
1) What can you learn about in genetics?
2) What might you like learning about?
3) What kinds of instructions are written in the DNA
language of life?
Gene/Allele GeneA gene is a working piece of DNA, one code for one protein molecule a cell can make written in the letters of DNA.
Allele
Alleles are different spellings for genes – and some spellings work better than others, and
some spellings are more common than others. You can think of alleles as the different
flavors or varieties of a gene. (example, different eye
shapes or colors spelled by diff. alleles)
4) Where do you find genes?
Genes are lined up on your chromosomes, each gene with
its own spot. So you inherit two alleles for each gene
(one on your mom’s chromosome and one on the one
you got from dad).
Heredity (think inherit-to get from your ancestors.)Heredity
Studying how characteristics are passed on from one generation to the next.
Of all the genes available to your species, in the fight to survive and reproduce, which
ones did your branch of the Tree of Life inherit?
Gametes = sex cells – eggs and sperm.
Gametes are different from all other cells because
GAMETES ONLY HAVE ONE SET OF CHROMOSOMES.
Every other cell in your body has pairs of chromosomes, one you got from mom, one from
dad. IN eggs and sperm, the pairs separate and combine to make a mixed single set of
chromosomes.
5) Why are gametes different from all other cells?
Chromosomes are just big pieces of DNA. Each chromosome contains certain genes.
For instance a chromosome may have the genes with the instructions to build hair proteins,
the proteins in your muscles, to control eye color, and many more. Another
chromosome will have genes controlling other traits and characteristics.
The colored bands in the drawing at right represent locations of genetic traits
on two pairs of chromosomes.
The location where a gene is found on a chromosome is called its locus (plural loci).
Different organisms have different numbers of Chromosomes.
Humans have 23 pairs of chromosomes for a total of 46.
23 come from our mother and 23 from our father.
6) What is a gene locus?
Trait/Characteristic/Phenotype
What your gene alleles do to you. How a piece of DNA makes you look, act, or function.
Genotype - says which genes do you have on your chromosomes.
Which 2 alleles you inherited from mom and dad.
The genotype is written as two letters, standing for the two alleles you have.
Phenotype – What your genes make you look like.
So if your GENOTYPE for eye color is BB, your phenotype would be having brown eyes.
Phenotype is what your genes make you look like or how well they make you work.
Homozygous – Homozygous simply means that you have two of the same allele for a trait.
BB or bb are examples of a homozygous phenotype (two Brown eye or two blue eye alleles.
Homo means same, so homozygous means your baby got two of the same allele when the
zygote was made.
Heterozygous – Hetero means different, so heterozygous means having two different
alleles.
Genotype-
Phenotype-
7a) What does the prefix homo mean?
7b) What does hetero mean?
8) What do alleles have to do with whether you are
homozygous or heterozygous?
Dominant Allele - an allele that always gets its way, is always is expressed.
So, you only need to inherit one dominant allele to show that trait.
In a Punnett Square, the dominant allele is always written as a capital letter.
9) What is a Trait?
Recessive Allele – an allele is covered by, or kept hidden by a more dominant gene.
A recessive allele will not be expressed, or show up, unless TWO copies are inherited.
10) What are synonyms for trait?
Fertilization - an egg cell is fertilized by a sperm cell. This fertilized egg cell is the first cell of 11) What do you call the first cell of a new living thing?
a new organism. It is a mixture of genes of the male and female parent that will combine
their genes and their traits.
12) Why is that cell so special?
Zygote – a fertilized egg, the first cell of a new organism.
In the zygote, the fertilized egg, for the first time, the genes that make you YOU, came
together. All of the billions of other cells in your body started with that one.
Purebred = True Breeding – True-breeding- basically means the same as homozygous –
having two dominant or two recessive alleles. When pure bred organisms interbreed (cross
with others of the same kind), all of their offspring will look like their parents.for whatever
genetic trait is being studied.
In the example on page 178, they show a cross breeding experiment starting with
two purebred pea plants, one with white and one with purple flowers.
Hybrid – A cross between two different purebred organisms. On page 178, they show an
F1 cross hybrid of a purebred purple plant and a purebred white plant. (Resulting in all
purple flowers since purple is a dominant allele.
Cross = in genetics this means to breed individuals of two different types.
For example to cross a plant that has one tall allele and one short allele with a
plant that has two short alleles.
Test Cross - A cross where you use a homozygous recessive organism to find out if the other
parent is homozygous or heterozygous.
Punnet Squares p 183-4
Punnet Squares are tools used to show the possible results of a cross –what will the
possibilities be for the offspring, and what are the odds of getting each type?
Pedigree a tool for tracing genes through a family line.