Unit 3 Pt 1: Genetics Grade 11 AP Bio (DNA)

Nucleotide

deoxyribose sugar + phosphate group + nitrogenous base

Nitrogenous bases

Adenine

Guanine

Cytosine

Thymine

Purines

Double-ringed structures

Adenine & Guanine

Pyrimidines

Single-ringed structures

Cytosine & Thymine

Bonding between bases

Hydrogen bonds

Adenine pairs with Thymine

2 hydrogen bonds

DNA Barcoding

Used to distinguish between/identify a particular species

Analyzed gene usually does not mutate

Analyzes a specific gene that is unique to the species

Discovered by Dr. Paul Herbert - 2003

Discovered at University of Guelph

Found that COI gene could be used to distinguish animal species

Steps of DNA Barcoding

1. DNA extraction

- DNA is extracted from organism's cells

2. PCR amplification of DNA barcode

- Target gene(barcode) is copied multiple times

- DNA sequencing

3. Sent to a sequencing company

- Sequence is read to identify nitrogenous bases

4. Identification

- DNA sequence is received

- Uploaded to a comparing service (i.e. BLAST)

- Service compares sequence to a database

Stages of Mitosis

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

Interphase

G1 - growth of cell, synthesis of organelles

Synthesis - replication of DNA

G2 - preparation for mitosis,

Prophase

Chromatin condenses into chromosomes

Centrioles migrate to opposite ends of the cell

Nuclear envelope dissolves

Metaphase

Centrioles at opposite ends of the cell

Spindle fibers attach to chromosomes

Chromosomes are lined up in the middle

Anaphase

Spindle fibers pull chromosomes apart

Centromeres split

Telophase

Two nuclear envelope forms

Cell membrane begins to pinch

Cytokinesis

Cell splits

Homologous chromosomes

Chromosomes with the same size and genes

Recombinant chromosomes

Chromosomes with recombinant DNA

Sexual reproduction

Requires 2 parents

Produces genetically distinct offspring

Fertilization

The fusion of male & female gametes(reproductive cells)

Zygote

The new cell with 46 chromosomes

Haploid cell

A cell with one set of chromosomes (one of each pair)

Represented by letter n

All gametes are haploid

Result from meiosis

Diploid cell

Has homologous chromosomes

Represented by 2n

All regular cells

Purposes of Meiosis

1. Genetic Reduction

2. Genetic Recombination

Genetic reduction

A form of cell division that produces daughter cells with half the number of chromosomes as the parent cell

Genetic recombination

When the products of meiosis have different alleles

Exchanging of alleles

Random(Independent) Assortment

Two equally probable arrangements at Metaphase I/II give rise to different chromosome combinations

Crossing over

Exchanging alleles between chromosomes

Only happens in Prophase I

Spermatogenesis

The process that produces sperm in males

Spermatogonia reproduce by mitosis then meiosis - starts during puberty

4 cells are produced

Oogenesis

The process that produces eggs in females

Egg cells reproduce by mitosis - before female is even form

1 viable cell is produced - 2 are inviable/polar

Begins meiosis but stops a prophase I

Multiple Births

More than one egg released

Creates fraternal twins

Single zygote splits

Types of Life Cycles (3)

1. Gametic Life Cycle

2. Zygotic Life Cycle

3. Sporic Life Cycle (Alternation of Generations)

Gametic Life Cycle

1. Fertilization

2. Cell becomes a zygote - undergoes mitosis and grows

3. Grows into larger organism - undergoes meiosis

4. Gametes are produced

Cycle repeats

Zygotic Life Cycle

1. Fertilization

2. Cell becomes a zygote - immediately undergoes meiosis

3. Gametes specialize into spores

4. Spores undergo mitosis

5. Organism grows (n)

6. Organism undergoes mitosis

- Produces gametes

Cycle repeats

Sporic Life Cycle (Alternation of Generations)

1. Fertilization

2. Zygote is produced - undergoes mitosis

3. Becomes a multicellular organism - undergoes meiosis

4. Spores are produced - undergoes mitosis

5. Becomes a haploid organism - undergoes mitosis

Cycle repeats

Karyotype

A picture of a person's chromosomes

Chromosomes are located, stained, examined

Usually taken from a white blood cell - duplicate quickly

Picture is taken from microscope

Rearranged by size

Important Characteristics for Karyotypes

What is the length of the chromosome?

- Organized in longest to shortest

Where is the centromere?

- Long arm is always down, short arm faces up

What is the banding pattern?

- Homologous chromosomes have the same banding pattern

Autosome

any chromosome that is not a sex chromosome

Sex chromosome

X or Y is responsible for the biological gender

X & Y chromosomes

Females only carry X chromosomes, only pass X to offspring

Father's sperm cells carry X or Y, determines sex

Different organisms have different numbers of chromosomes

Hemizygous chromosomes

Partially homologous chromosomes

(XY)

Karyotype Use

can determine if an individual has chromosomal disorders

Type of Errors in Chromosome Number

Non disjunction

Point mutation

Chromosomal Rearrangement

Non-disjunction

When chromosomes or sister chromatids do not separate during meiosis

Anaphase I or Anaphase II

Produces gametes with too few/many chromosomes

Can occur in either sperm or egg cell

Point mutation

When a single DNA base pair is copied incorrectly during interphase

Chromosomal Rearrangement

When chromosomes exchange and unequal amount of DNA

One gains genes and the other loses

Occurs in prophase I

Barr body

A small bar in the nucleus that rolls up the second X chromosome and doesn't use it

3 Autosomal Human Trisomys

Trisomy 13 - Pautau's Syndrome

Trisomy 18 - Edward's Syndrome

Trisomy 21 - Down's Syndrome

Trisomy 13 - Pautau's Syndrome

3rd chromosome for Chromosome 13

95% are not born

95% do not live past the age of 1

Physical malfunctions

Cleft palate

Smaller cranium

Trisomy 18 - Edward's Syndrome

3rd chromosome for Chromosome 18

Cannot usually live past 2

Trisomy 21 - Down's Syndrome

Has an extra chromosome

Diagnosed by taking a sample of cells in the womb

Only survivable trisomy

3 Sex Chromosome Trisomys

Trisomy XXY - Klinefelter's Syndrome

Trisomy XXX - Normal female

Trisomy XYY - Taller than average male

+

Monosomy X - Turner's Syndrome

Trisomy XXY - Klinefelter's Syndrome

XXY chromosomes

Sterile

Lack of facial hair

Trisomy XXX

Normal female

Barr body rolls up two X chromosomes instead of one

Trisomy XYY

Taller than average male

Taller in comparison to family members

Monosomy X - Turner's Syndrome

Only have an X chromosome

Webbed Neck

Types of Chromosomal Mutations

Insertion Mutation

Translocation Mutation

Deletion Mutation

Duplication Mutation