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AP Genetics
Notes on genetics
69
Biology
12th Grade
12/18/2011

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Term
Genome
Definition
ENTIRE genetic makeup
Term
Locus
Definition
Location of a gene on a chromosome
Term
Haploid Majority
Definition

Occurs mostly in Fungi and Protists

They can join together to form diploid cells

Term
Diploid Majority
Definition

Seen in animals

Parents make haploid gametes and are stored in reproductive organs.

They reunite through sex and the DNA combines forming another organism.

Term
Somatic cells make up most of our body
Definition
"soma" means body
Term
How many chromosomes do somatic cells have
Definition
46
Term
Homologous Chromosomes are also called
Definition
Autosomes
Term
How masny pairs of Autosomes are there?
Definition
22 pairs= 44 Chromosomes
Term
What is the X/Y makeup of a female?
Definition
XX
Term
What is the X/Y makeup of a male?
Definition
XY
Term
In a males "XY" Chromosomes are called
Definition
Heterologous
Term
Germ cells (gametes)
Definition

These are sex cells (male-sperm/female-egg)

They are haploid

Egg and Sperm fertilize to form a diploid cell called a zygote.

 

Term
What does a zygote undergo to form a new organism
Definition
Mitosis
Term
Meiosis
Definition

A lot like MITOSIS.

There are 2 sets of division leaving you with 4 exact cells.

Occurs in the gonads.

The S phase doubles the # of chromosomes.

 

Males produce 4 sperm and females produce 1 egg.

 

Term

3 Major differences between 

MITOSIS AND MEIOSIS

Definition

Crossover

Chromosome PAIRS seperate in Anaphase I

Sister chromatids seperate in Anaphase II

Term
Crossover
Definition

Genetic swapping between homologous chromosomes.

This occurs to create variation

SYNAPSIS- Chromosomes intertwine together

Tetrad-4 chromosomes twist together

Chiasmata- Chromosomes physically overlap

Term
Character
Definition
An inheritable physical feature
Term
Trait
Definition

Requires 2 allels (one from each parent)

Variation of character

Term
Allels 
Definition

Different version of a gene

2 allels are needed for 1 trait

Dominant allels have capital letters

Recessive allels have lower letters

Term
True Breed
Definition

Only have one type of allels for a certain trait (BB or bb)

Otherwise known as Homozygous allels.

Term
Hybridization
Definition

Creates an organism with 2 types of allels. (Bb)

Otherwise known as Heterozygous allels.

Term

Phenotype

Pheno=PHYSICAL

Definition

Refers to a physical trait that can be seen.

(Blood Type or eye color)

Term
Genotype
Definition

Organisms genetic makeup for a certain trait.

(BB, Bb, bb)

If genotype is unknown, perform a testcross to find it.

Test cross must be done with a homologous recessive allel so that the unknown will not have genetic makeup covered.

Term
Punnett Square
Definition

A chart that shows the possible genotypic outcome based on the parents genotypes.

MONOhybrid=1 trait=4 squares=4^1

DIhybrid=2 traits=16 squares=4^2

TRIhybrid=3 traits=64 squares=4^3

Term
Mendels law of Segregation 
Definition

The genes on chromosomes can move independently of one another.

This is supported by what is happening in crossover during Anaphase I of Meiosis.

Term
Mendels law of independant assortment
Definition

This states that the chromosomes move independantly of one another.

Occurs in Anaphase 1 and 2

And in Mitosis 

Term
Probability
Definition

Chance that certain outcome will actually happen.

Probability ranges from 0 and 1.00 (0%-100%)

 

Term
Incomplete Dominance
Definition
This is where one phenotype does not dominate and both are seen in a blended version.
Term
Complete Dominance
Definition
The dominant allel has total control over the recessive allel. Only 1 is seen.
Term
Codominance
Definition

Both allels are seen, but they ARE NOT BLENDED.

They are equally present in terms of phenotype.

Term
Multiple Allels
Definition

There are MULTIPLE versions of the same basic allel.

Variations of Blood Types for ex.

Term
Pleiotropy
Definition
This is where 1 gene affects multiple phenotypes.
Term
Epistasis
Definition

A gene at 1 LOCUS affects a gene at a 2nd LOCUS

Hair is a good example. color, texture, thickness

Term
Polygenic Inheritance
Definition

MANY different degrees of phenotypic outcomes.

This is due to Quantitative Characters (How many allels you recieved from your parents)

Skin Color for ex.

Term
Multifactorial
Definition
Many environmental factors are affecting the phenotypic display of genes in that organism.
Term
Pedigree
Definition

Family history of trait occurance in chart form. Affected individuals are SHADED in the chart.

These help tell the past occurance and can be helpful when trying to predict the future occurance through mating.

Term
Recessive Disorders
Definition

NO INFORMATION inherited on both chromosomes.

EXTREMELY HARMFUL

 

ONLY OCCUR in the homologous recessive state.

Nothing is there to dominate the disorder.

 

Term
Carriers
Definition

Heterozygous in genotype

They have a 50% chance of passing the trait along ( If the sperm and egg both are homozygous recessive then the trait will pass on to the opffspring)

Term
Cystic Fibrosis
Definition

Most common lethal disease

1 in 2500 births

In caucasions, 1 in 25 is a carrier.

Creates faulty Chloride ion (Cl-) protein carrier on cell membranes in the lungs.

This causes fluid to build up in the lung tissues.

People drown in their own fluid

There is NO CURE

Term
Tay-Sachs Disease
Definition

Creates a non-functional lysosome in brain cells.

Brain cells need a lot of energy to function properly. Therefore the feed off on lipids primarily.

Lysosomes break down lipids, but the lysosomes in this disorder are missing an enzyme that helps do this, so the lysosomes fill of with lipids then die.

Affects Jews a lot bc of marrying within the culture

Children affected die a painful death usually by the age of 5

Term
Sickle-cell Disease
Definition

Most common within Black population.

Affects 1 in 400 births

The 6th amino acid is changed (Glutein-->Valine) in the PRIMARY  sequence of one of the proteins needed to make red blood cells.(666 is BAD; changing the 6th amino acid is BAD)

Term
Sickle-cell trait
Definition

Are resistant to Malaria bc of the 1 recessive allel but they mostly have normal red blood cells for carrying O.

This is also refered to as Heterozygous Advantage


Term
Dominant Disorders
Definition

ONLY NEED 1 ALLEL FOR THE DISEASE TO BE EXPRESSED

If the individual in homozygous dominant, then the disease in normally fatal

Term
Achondroplasia
Definition

Genetic Dwarfism

Affects 1 in 10000 births

Term

Huntingtons Disease

 

Definition

Affects 1 in 10000 births

Not apparent until the 40s and 50s

The dominant gene has a locus on tip of autosome 4

Family history is important in the diagnosis of this disorder.

Almost always fatal

Term
Multifactorial Diseases
Definition

Heart Disease

Diabetes

Cancer

Alchoholism

Term
Genetic Counselors
Definition

Individuals who run PEDIGREES using family history data to look at potential outcomes and to give advice on whether the parent should attempt at concieving a child.

They can use Amniocentesis, Chorionic Villus Sampling, Ultrasound, Fetoscopy, and Newborn Screening for conformation that the offspring does/doesnt have disorders.

Term
Linked Genes
Definition
Refers to genes found on the autosomes. These are usually inherited as a LINKED unit bc they are found on the same chromosome.
Term
Genetic Recombination 
Definition

Can occur at crossover in Prophase 1 or when chromosomes seperate.

Parental types look like their parents

Recombinant types look like a combination of both parents.

Term
Cytological Maps
Definition
Locate genes loci base on banding strain pattern.
Term
Sex Linked Genes
Definition

Genes found on the sex chromosomes. 95% refers to the X (seX linked)

Sex chromosomes undergo very little crossover in Prophase 1 of Meiosis.

Sex of organism will be determined at conception.

Everyone is female at first

Term
Types of: Patterns of Inheritance and Sex Linked GENETIC disorders.
Definition

COLOR BLINDNESS

MUSCULAR DYSTROPHY

HEMOPHILIA

 

Due to males having X and Y, if they get a recessive gene with a disease, they will not have a dominant gene to cover it up, resulting in more males with Inheritance/SexLinked Diseases

Term
X Inactivation
Definition
Only occurs in females.
Term
Chromosomal Errors
Definition

Chromosomal Number: failure to seperate during anaphase.

 

Individual Chromosome Structure: occur bc of faulty crossover.

Term
Syndrome
Definition

refers to an organism possessing the traits of a particular genetic disorder.

Downs: Extra 21 autosome

Klinefelters: XXY both penis and vagina

Turners: XO underdeveloped vagina

Cri du Chat: part of 5 is deleted. windpipe 

Leukemia: translocation between 9 and 22. cancerous white blood cells.

Fragile X: heavy methylation on X. mental

Term
Genomic Imprinting
Definition

Erasing your parents DNA and creating your own.

Too much methylation=doesnt look like parents

not a lot= similar

Term
Extranuclear DNA
Definition
DNA located outside of the nucleus.
Term
DNA Replication
Definition

The process of making a complete copy of an entire length of DNA.

Occurs during the S phase. of the cell cycle.

It is easy to do for cells, bc both sides are complementary.

A=T  G=C

EXTREMELY quick

Term
Origins of Replication
Definition

Specific nucleotide sequences in the DNA strands that act as staring points.

The enzyme helicase unwinds the DNA double helix to create a Replication Bubble.

The ends of the bubbles are called replication forks.

Work is happening on both sides of the forks and bubbles.

Many bubbles can be on the same DNA strand.

Term
DNA Replication Elongation
Definition
Elongation of the new DNA complimentary side will require the enzyme DNA Polymerase III to add the new nucleotides to the new DNA complementary side. It also acts as a proof reader checking for errors.
Term
DNA Nucleosides
Definition

brought to the enzyme from the cytoplasm of a cell.

A nucleoside has 3 phosphates to supply the bonding process with energy.

The Nucleoside will lose 2 phosphates in the bonding process.Loss of phosphates make it a nucleotide.

This saves ATP for other cellular processes.

Term
DNA is always read and made 5'-->3'
Definition

The 5' carbon of the sugar has a phosphate attached to it

The 1' carbon of the sugar has the nitrogen base attached to it.

The 3' carbon of the sugar has an open bond

Term
Helicase
Definition
unwinds DNA
Term
Single-stranded binding protein
Definition
keeps the 2 sides appart and stable.
Term
Lead strand of the replication fork (2 forks going in opposite directions) 
Definition

The strand runs in a 5' to 3' direction as it opens.

In order to start adding nucleosides, attach RNA PRIMER using PRIMASE  AND GO!

Lead strands on both sides of the replication bubble are located diagonally from each other. This is bc the 2 DNA strands are anti parallel.

Term
Lagging Strand 
Definition

THIS SIDE IS NOT RUNNING 5'TO3' therefore it laggs.

This fork has to wait for a long segment of DNA before adding a primer.

Once helicase opens and the RNA primer attaches and then DNA Polymerase III works backwars forming Okazaki fragment.

The O fragments are stiched together using Ligase.

They are located diagonally also.

Term
DNA Error/Repair
Definition

used when the wrong nucleotide is added to the sequence. DNA Polymerace will reverse a spot, removing the wrong nucleotide.

 

NUCLEOTIDE ESISION REPAIR

1.Nuclease cuts around so they can be removed

2. DNA replaces

3. Ligase stiches together.

Term
Telomeres
Definition

Are repeated nucleotide sequences found at the end of each chromosomes used for RNA primers to attach and start replication w/o bubble.

Number of telomeres depends on cell type.

Having telomeres protects from erosion.

APOPTOSIS is programmed cell death

Term
Telomerase
Definition

This is the enzyme that replaces telomeres during fatal developement. After the fetus is developed this enzyme shuts off.The DNA segment that is responsible for providing the blueprint will become heavily methylated.

Tumors can be formed when the enzyme is turned back on.

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