Unit 4 (Genetics) Exam Outline Flashcards
Genetics
Study of patterns in heredity and the variation of organisms.
Heterozygous
two letters are different
Genotypes
genetic makeup of an organism, consists of alleles that the organism inherits from its parents (the letters)
Sex chromosomes
A chromosome that determines sex (gender)
Crossing over
When 2 homologous chromosomes pair together and they cross each other. Some segments break off and reattach to the other chromosome.
Somatic mutation
take place in an organism’s BODY cells and can therefore affect the organism.
Ex: certain types of skin cancer and leukemia results from somatic mutations.
Somatic mutations are NOT passed on to offspring.
Universal donor
Type O blood, anybody can receive it because it has no antigens (substance that stimulates as immune response.) Can only take type O blood.
Gene
a segment of DNA that contains coding for a polypeptide or protein; unit of hereditary information
Incomplete dominance
heterozygous individual expresses both simultaneously WITH blending
ex: red flower & white flower = pink flower
Sex linked
Traits whose genes are carried on an x or y chromosome.
Germ-cell mutation
occur in the gametes (sperm and
egg cells). They can be inherited by the offspring but do not affect the individual themself.
Chromosome mutation
either changes in the structure of a chromosome, or the loss of an entire chromosome.
See section 12-6 (page 225) of old text.
Universal acceptor
Type AB blood because it can accept A, B, AB, or O blood, can only give to other type AB’s
Alleles-
versions of a trait
Mendel’s factors are now called alleles. Controls the characteristics
The letters that show the genes from mom or dad. Alternate versions of a trait.
(One letter?)
Phenotype
Appearance of an organism as a result of its genotype.
Ex: PP, Pp = purple flower
pp = white flower
Autosomes
A chromosome that is not a sex chromosome. (Controls other traits)
Linkage-
The genes located on one chromosome form a linkage group. Because they are on the same chromosome they tend to be inherited together.
Gene mutation
Occurs when a single nucleotide (makes up DNA) is substituted, added or removed
Pedigree
A diagram of the genetic history of an individual; can show how a trait is inherited over several generations.
Mutation
a change (or error) in the DNA of an organism.
Mutations can involve an entire chromosome or a single
DNA nucleotide (A C T G) and can take place in ANY cell.
Somatic mutation
take place in an organism’s BODY cells and can therefore affect the organism.
Ex: certain types of skin cancer and leukemia results from somatic mutations.
Somatic mutations are NOT passed on to offspring.
Lethal mutation-
Cause death, often before birth.
Ex: any mutation that causes a miscarriage.
Ex: Albinism in wild animals would result in death shortly after birth because the animal would develop skin cancer faster, and be more vulnerable to predators.
Chromosome mutation
either changes in the structure of a chromosome, or the loss of an entire chromosome.
See section 12-6 (page 225) of old text
Gene mutation
Occurs when a single nucleotide (makes up DNA) is substituted, added or removed
Segregation
Pairs of gene variants are separated into reproductive cells.
Independent assortment
During meiosis, the random distribution of genes from different chromosomes to gametes.
Linked
Two or more genes on the same
chromosome are said to be LINKED. Because they are on the same chromosome, linked genes tend to be inherited together - this is the OPPOSITE of Mendel’s Law of Independent Assortment!
Karyotype
photomicrograph of the chromosomes in a dividing cell found in a normal human. Notice that the 46 human chromosomes exist as 22 homologous pairs of autosomes and 2 sex chromosomes (XX in female, XY in males. See Fig 8-3 p147 of old text.
Huntington’s disease
uncontrolled movement of the arms, legs, head, face and upper body
an inherited disorder that causes nerve cells (neurons) in parts of the brain to gradually break down and die. The disease attacks areas of the brain that help to control voluntary (intentional) movement, as well as other areas.
Hemophilia
a rare disorder in which the blood doesn’t clot in the typical way because it doesn’t have enough blood-clotting proteins (clotting factors). If you have hemophilia, you might bleed for a longer time after an injury than you would if your blood clotted properly.
Cystic Fibrosis
Mucus clogs lungs; liver and pancreas; victims usually don’t live to adulthood.
a genetic condition that affects a protein in the body. People who have cystic fibrosis have a faulty protein that affects the body’s cells, its tissues, and the glands that make mucus and sweat. Normal mucus is slippery and protects the airways, digestive tract, and other organs and tissues.
How crossing over can affect the expected ratios (read section on Linkage groups on pages 222-223)
Crossing over causes the F2 generation to have many offspring with the recessive traits instead of lots with the dominant traits. This meant there had to be some kind of change for this to have occurred. This could have been caused by a mutation but that only happens in a small percentage of offspring and this happened in a large amount. The alleles became rearranged so recessive traits became more common.
