Everything there is to know about DNA

MitosisMeiosis

RNA synthesisGenetic engineeringMendelian genetics

Mitosis = cell cyclea. Process through which a body

cell replicates itself.b. Process produces two NEW body

cells.c. Cells must be identical to each

other.d. Process takes place continuously,

at the rate of once every 24 hours

Mitosis is controlled by the codesfound on DNA. DNA is found onchromosomes.

There are many interchangeable terms that are used to talk aboutgenetic codes.

DNA = DEOXYRIBOSE NUCLEIC ACIDCHROMOSOMES = GENERIC TERM TO MEANTHE CODES FOUND ON DNA.CHROMATID = A PAIR OF CHROMOSOMES:

CHROMATIN= A PAIR OF CHROMATID

CENTROMERECHROMATID

MITOSIS involves 6 steps.

1. Interphase – longest phase “resting” phase

cell matures organelles develop process begins:

nuclear membrane breaks down

DNA duplicatesorganelles replicate

DNA DUPLICATION

DNA is composed of: phosphate groups –PO3

ribose group nitrogen bases:

thiamineadenineguanine cytosine

thiamine always bonds with adenineguanine always bonds with cytosine

C G

T A

A TG C

C G

A T

T A

PHOSPHATE

RIBOSE

T

A G

C

C

A

T

A

TC

G

G

T

A

T

A G

C

C

A

T

A

TC

G

G

T

A

A

TC

G

G

T

A

T

A G

C

C

A

T

2. Prophase – chromatin become visible centrioles appear

spindle fibers appear chromatin begin to move

3. Metaphase – chromatin line up alongequator of cell

prepare to separate

4. Anaphase – chromatin separate to becomeindividual chromatid.

2. Prophase – chromatin become visible centrioles appear

spindle fibers appear chromatin begin to move

3. Metaphase – chromatin line up alongequator of cell

prepare to separate

4. Anaphase – chromatin separate to becomeindividual chromatid.

2. Prophase – chromatin become visible centrioles appear

spindle fibers appear chromatin begin to move

3. Metaphase – chromatin line up alongequator of cell

prepare to separate

4. Anaphase – chromatin separate to becomeindividual chromatid.

2. Prophase – chromatin become visible centrioles appear

spindle fibers appear chromatin begin to move

3. Metaphase – chromatin line up alongequator of cell

prepare to separate

4. Anaphase – chromatin separate to becomeindividual chromatid.

INTERPHASE

PROPHASE

METAPHASE

- - - - - - - - - - - - - - - - - - - - - - - - - - -

ANAPHASE

- - - - - - - - - - - - - - - - - - - - - - - - - -

TELOPHASE

CYTOKINESISThere are now two newcells that are identicalto each other.They contain the ribosomesand mitochondria madeduring interphase.The cells will now begin theprocess of producing theorganelles that are not yetpresent in the cell, like …

When all the organelles arepresent, the cell will enterinterphase and the processwill begin all over again.

INTERPHASE

Meiosis

Reduction Division

Meiosis is the process by which gametes arecoded with inheritable traits.

Remember: for every genetic trait, an organism must inherit 2 alleles - one from the father andone from the mother.

In sexual reproduction, an offspring is the resultof the union of two cells - an egg and a sperm.

These two cells are called gametes. Each gametecontains one allele for each inheritable trait.

Mitosis: production of body cells one duplication of DNA

one cell division resulting cell contains all the DNA

of the parent cell - diploid resulting cell contains both

alleles for each trait human cell: 46 chromosomes

23 pairs = 2 alleles for eachtrait

diploid number

Meiosis: production of gametes one duplication of DNA two cell divisions

resulting cell contains half theDNA of the parent – haploid

resulting cell contains one allelefor each trait.

Gamete = sperm/egg 23 chromosomes1 allele for each traithaploid number

23 23 46

Egg sperm offspringHaploid # haploid # diploid #One allele one allele two alleles

46

92

46 46

2323 23

23

4 gametes each with the haploid number

BR

d

R

w

BR

Wd

bR

dw

Egg - haploid Sperm - haploid

Diploid

Eye color Bb heterozygoous

Hair color RR homozygous dominant

Dimples dd homozygous recessive

Widow’s peak Ww heterozygous

Wd

b

BR

Wd

bR

dw

Br

DW

Br

DW

BR

Wd

bR

dw

Br

DW

Br

DW

Offspring

B b

B

B

BB Bb

BB Bb

R Rr

r

Rr Rr

Rr Rr

RNA and PROTEINSYNTHESIS

There are two types of nucleic acids:

1. DNA

2. RNA

Let’s review a few terms:

Protein: structure: long chain of C,H, O, N, and S Amino acid: building blocks of proteins structure: made up of 3 nitrogen bases function: necessary for cellular growth and repair large covalent molecules produced in the ribosomes enzymes-speed up chemical reactions.

Enzymes-specific for compounds they digest.Without these enzymes, the matching compounds will not be digested or broken down.Because these enzymes are specific there mustbe a code for their production.

Lactase - lactose.

Amylase - simple starches

Pepsin - food proteins

RNA will provide the code for proteinsynthesis. Each protein performs a specificfunction and therefore requires a specificcode. This code will come from DNA.

DNA:

A T

C G

G C

A T

T A

G C

DNA code is found in the …..Proteins are made in the ……

DNA:

T

G

C

T

A

C

A

C

G

A

T

G

DNA:

T

G

C

T

A

C

A

C

G

A

T

G

mRNA

A

C

G

A

U

G

DNA:

A

C

G

A

T

G

mRNA

A

C

G

A

U

G

tRNA

U G C U A C

DNA:

A

C

G

A

T

G

mRNA

A

C

G

A

U

G

tRNAU G C U A C

rRNAACGAUG

rRNAACGAUG

Ribosomal RNA or rRNA now has theCode it needs to make specificProteins needed by the organism.The code for this rRNA is ACGAUG. EachLetter stands for a nitrogen base. TheRibosome will ‘read’ the nitrogen basesIn groups of three. Every three nitrogenBases = an amino acid. Several aminoAcids grouped together = a protein.

ACG = amino acid = threonineAUG = amino acid = methionine

Mendellian geneticsGregor Mendel

The father of geneticsMonk

Gardener

Heredity - process through which traits are passed on from one generation to another.

Trait – any visible or invisible characteristic, function, or process that is a necessary part of an organism.

Gene –structure that contains the code for every trait.

DNA

Allele – particular form of a trait. There are at least two alleles for every trait:

one dominant one recessive

Dominant – the allele for a trait that is ALWAYS seenin the organism.

Recessive – the allele for a trait that can be masked bythe dominant trait.

Every chromosome (2 chromatids) will be composedOf two alleles!

chromatid

Allele 1 Allele 2Allele 1 and allele 2 are carrying the codes for the same trait. One allele comes from the mother, the other from the father.

Dominant – the allele for a trait that is ALWAYS seenin the organism.

Recessive – the allele for a trait that can be masked bythe dominant trait.

Every chromosome (2 chromatids) will be composedOf two alleles!

chromatid

Allele 1 Allele 2Allele 1 and allele 2 are carrying the codes for the same trait. One allele comes from the mother, the other from the father.

Combinations of alleles result in what an offspringinherits. And what an offspring inherits determineswhat the offspring looks like and how that offspringfunctions.

POSSIBLE COMBINATIONS:

HOMOZYGOUS

HETEROZYGOUSbB

bb

BB

COMBINATIONS OF ALLELES WILL DETERMINEWHAT THE OFFSPRING LOOKS LIKE =

PHENOTYPE.

COMBINATIONS OF ALLELES WILL DETERMINE THEWAY AN OFFSPRING FUNCTIONS, I.E. ITS CODE=

GENOTYPE.

THERE ARE THREE TYPES OF GENOTYPE:HOMOZYGOUS DOMINANTHOMOZYGOUS RECESSIVEHETEROZYGOUS

Homozygous dominantGene carries two dominant alleles for any trait Phenotype: red flower Genotype: RR (purebred)

Homozygous recessiveGene carries two recessive alleles for any trait. Phenotype: white flower Genotype: rr (purebred)

HeterozygousGene carries one recessive allele and one dominant allele Phenotype: red flower Genotype: Rr (hybrid)

Heredity and genetics are processes that involve chance=probability-the chance of something happening.

Traits are inherited by the passing on oftwo alleles-either dominant or recessive or both.

This inheritance and chance are predicted by using punnett squares.

Punnet square--used to predict possiblegenotype of an offspring when the genotype of the parents is known. Once genotype is known, the phenotype willbe decided. father

mother

25%Chance ofan offspring

25%Chance ofan offspring

25%Chance ofan offspring

25%Chance ofan offspring

R R

r

r

Mother :Phenotype whiteGenotype homozygous recessive

Father:Phenotype redGenotype homozygous dominant

Rr25%

Rr25%

Rr25%

Rr25%

Offspring: 100% heterozygous - genotype 100% red - phenotype

mother

father

Mother: Father:Phenotype: short Phenotype: tallGenotype: homozygous recessive Genotype: heterozygous

T t

t

t

Tt tt25% 25%

Tt tt25% 25%

Offspring: 50% tall 50% short - phenotype 50% heterozygous - genotype 50% homozygous recessive - genotype

Red sweet pea White sweet pea Pink sweet peaHomozygous Homozygous HeterozygousDominant recessive