THE

CENTRAL

DOGMA OF

BIOLOGY

1. DNA B4.2

The genetic information encoded in DNA molecules provides

instructions for assembling protein molecules.

Genes are segments of DNA molecules. Inserting, deleting, or

substituting DNA segments can alter genes.

An altered gene may be passed on to every cell that develops

from it.

The resulting features may help, harm, or have little or no

effect on the offspring’s success in the environment.

2.DNA TERMS

1. DNA—deoxyribonucleic acid, genetic material for almost

all living things

2.Nucleotide –monomer of nucleic acid, made up of a five

carbon sugar, a phosphate group, and a nitrogenous base

3. Nitrogenous bases – adenine, guanine, cytosine, thymine,

and uracil

4.Double-helix – twisted double ladder, shape of DNA

5. Genes – unit of heredity, located on chromosome

DNA TERMS

6. Amino acid –- strung together to make protein

7. Polypeptide – polymer of many amino acids linked

together by peptide bond

8. Transcription – process of mRNA being made from DNA

template

9. Translation – process of ribosomes using the sequence of

mRNA to create a sequence of amino acids that will form a

protein

10. Mutation – change in DNA sequence that affects the

genetic information

3. INHERITED

MUTATIONS

When mutations occur in sex cells, they can be passed on to

offspring (inherited mutations), but if they occur in other

cells, they can be passed onto descendant cells only

(noninherited mutations). (B4.2A)

1. GAMETES (SEX CELLS)

a. Made by meiosis for the sole purpose of sexual reproduction.

b. Sperm and egg will fuse to form an entire new living organism.

c. So if a mutation occurs to the chromosomes in a gamete cell then the mutation will be passed onto the offspring.

2. SOMATIC CELLS (NORMAL BODY

CELLS)

a. Made by mitosis for the purpose to making cells that are identical

b. Daughter cells are identical parent cells

c. If a mutation occurs to the chromosomes in a normal body cell all the cells that descend from it will have the mutation, not the entire organism.

4. EVERY SPECIES HAS ITS OWN

CHARACTERISTIC DNA SEQUENCE.

(B4.2B)

1. Each species has its own specific DNA sequence that

determines all the special characteristics of the species.

**the base pair can occur in any order

**total possible nucleotide sequences is

4140000000

2. The Human Genome Project

a. constructed a map that showed the sequence of

base pairs along our chromosomes and

b. showed the sequence of genes along the human

chromosome

5. DESCRIBE THE

STRUCTURE AND

FUNCTION OF DNA.

(B4.2C)

1. Structure

i. Double-helix – DNA is a twisted ladder

ii. Sugar(Deoxyribose) phosphate backbone make up the

sides

iii. Hydrogen bonded bases make up the rungs or steps of

the ladder

1.Nitrogenous bases: adenine, guanine, cytosine, and thymine

2.In each species the amount of A=T, and C=G

2. Function

i. Stores information to be passed from one generation to the

next

ii. Is replicated

iii. And undergo mutations

6. DNA REPLICATION

1. Replication – making a copy of DNA

-- occurs during S-phase of the cell

cycle before cell division

--parent DNA molecule unwinds and

unzips

--each old strand acts as template for

a new strand

--semiconservative = each new

strand contains an old and a new

strand

DNA REPLICATION

A. PROKARYOTES

1. single DNA loop

2. replication can take place in either a single direction or both directions around the loop, depending bacteria type

3. able to replicate in 20 minutes

B. EUKARYOTES

1. DNA replication begins at numerous origins of replication along the length of the chromosomes creating a replication fork that brings the strand back together

2. takes a few hours to copy all 6 billion base pairs found in humans

REPLICATION

i. Unwinding—the old stands that make up the parent DNA

molecule are unwound and unzipped

1. Helicase is the enzyme that breaks the

hydrogen bonds between bases

REPLICATION

ii. Complementary base pairing – new complementary

nucleotides, always present in the nucleus, are positioned by

the process of complementary base pairing

1.DNA polymerase enzyme that joins bases together

REPLICATION

iii. Joining – The complementary nucleotides join to form

new strands.

1.Each daughter DNA molecule has one strand

and one new strand

a. Semiconservative – each new strand has

one old strand and new strand.

REPLICATION

**For the “DNA” sequences create the replicated DNA

strands, using complementary base pairs

ATCGACCTAACCGGAGTACCTTAATTAAGCATCT

TAGCTGGATTGGCCTCATGGAATTAATTCGTAGA

7. DNA, RNA, AND

PROTEIN SYNTHESIS

B4.2X

Protein synthesis begins with the information in a sequence

of DNA bases being copied onto messenger RNA.

This molecule moves from the nucleus to the ribosome in the

cytoplasm where it is “read”.

Transfer RNA brings amino acids to the ribosomes, where

they are connected in the correct sequence to form a specific

protein.

PROTEIN SYNTHESIS

TERMS

Protein synthesis – process of making proteins using mRNA

and tRNA to join together amino acids in peptide bonds

RNA – ribonucleic acid, sugar(ribose), phosphate, and

nitrogenous bases (guanine, adenine, cytosine, and Uracil

instead of thymine), and single stranded

mRNA—serve as messengers from DNA, acts template for

protein

PROTEIN SYNTHESIS

TERMS

tRNA – brings amino acid that matches mRNA

rRNA – holds the mRNA-tRNA complex together at the

ribosome

codon – three consecutive nucleotides

8. THE CENTRAL

DOGMA OF BIOLOGY

A. Says that the genetic information in DNA molecules

provides instructions for assembling protein molecules and

that this is virtually the same mechanism for all life forms.

(B4.2f)

B. Describes the processes of replication, transcription, and

translation and how they relate to each other in molecular

biology. (B4.2g)

CENTRAL DOGMA OF

BIOLOGY

**Central Dogma of Biology

--Proteins come from RNA and RNA comes from DNA

--So DNA specifies the production of proteins!!!

--Genetic code is universal

--Each codon is made of three DNA nucleotides

--Except for stop codons all codons code for amino

acids

9. TRANSCRIPTION

a. Transcription – making mRNA from a strand of DNA

i. Occurs in nucleus

ii. Complementary RNA is made from DNA

iii. Uses the enzyme RNA polymerase

1.Breaks the hydrogen bonds between bases of DNA at the

promoter (origin of transcription)

2.Unwinds, unzips, and complementary RNA nucleotides are

joined together

TRANSCRIPTION

iv. after RNA polymerase (at the terminator – stops

transcriptions) passes the original DNA retakes its shape

v. The mRNA is modified after its production to optimize its

production of proteins

1. Introns – segments of DNA that never get

expressed

a. Get cut out

2. Exons – segments of DNA that get expressed

3. Spliceosomes – result of the clipping and splicing

of introns and exons to produce “mature” mRNA

10. TRANSLATION

A. Translation – mRNA is involved in protein synthesis

i. Takes place in the cytoplasm

ii. Sequence of mRNA at a ribosomes directs the

sequence of amino acids

iii. tRNA bind with one particular amino acid

(anticodon)

TRANSLATION

iv. tRNA is complementary to mRNA

v. at least one tRNA molecule for each of the amino acids

vi. carried out by amino acid activating enzymes – tRNA

synthases

TRANSLATION

vii. peptide bonds form between amino acids that have been

strung together at the ribosome by matching codons of

mRNA and anticodons of tRNA

viii. start codon is always AUG – methionine

ix. stop codons—do not specify an amino acids

--UAA, UGA, UAG

**Using the following original DNA sequence TAC TTT TGG

--Transcribe the mRNA codons

--state the amino acids

--Translate the tRNA anticodons

11. TRANSPOSONS =

“JUMPING GENES”

1. Groups of genes that move and can alter the expression of surrounding genes, to either increase or decrease normal function.

a. May cause uncontrolled cell growth indicative of cancer

b. Cause localized mutations

c. Carry genes that lead to translocation, deletions, and inversions of genes on chromosomes

d. Leave copies of themselves behind that can cause chromosomal duplication

e. Contain genes that may make a bacterium become resistant to antibiotics

** may be source of evolution…

12. MUTATIONS

i. Spontaneous – happen for no apparent reason

1.ONLY ONE MISTAKE IN ONE BILLION

NULCEOTIDES is due to problems with DNA

replication

13. ENVIRONMENTAL

MUTAGENS – AGENT

THAT INCREASES THE

CHANCES OF MUTATION

1. Carcinogens – cancer causing agents

a. Tobacco

b. Radiation

i. X-rays

ii. UV light

iii. Radon

c. Alcohol

d. Asbestos

e. Vinyl chloride

f. Formaldehyde

g. Hormone therapy

h. Nitrites in food (hotdogs, beef jerky, etc)

i. Smoked foods

j. Salt-cured foods

k. Viral infection

i. HPV changes the cells of the cervix leading to increase chances of cervical cancer

14. THE CONSEQUENCES

THAT CHANGES IN THE

DNA COMPOSITION OF

PARTICULAR GENES MAY

HAVE ON AN ORGANISM

(E.G. SICKLE CELL

ANEMIA, OTHER). (B4.2D)

1. Genes specify a polypeptide

2. If the gene is changed then the polypeptide is changed

3. One gene—one polypeptide hypothesis

15. THE EFFECTS (ON THE GENES)

OF EXPOSING AN ORGANISM TO

RADIATION AND TOXIC CHEMICALS.

(B4.2E)

1. Mutation – change in DNA

-Due to a change in base sequences

-Changes lead to malfunctioning proteins

-Effect on phenotype of organism can be dramatic or

even lead to the development of cancer

16. MUTATIONS –

CHANGES IN THE

GENETIC MATERIAL

1. Gene mutations -- change in a single gene

A. Point mutation -- changes in one

or a few nucleotides

*Substitution-- one base is changed

to another

--Usually one affects one amino

acid

--By inserting, deleting, or substituting DNA segments can

gene can be altered.

--An altered gene may be passed on to every cell that

develops from it and that the resulting features may help,

harm, or have little or no effect on the offspring’s success in

its environment. (B4.4a)

-- Mutations in the DNA sequence of a gene may be silent or

result in phenotypic change in an organism. (B4.4c)

2. Chromosomal mutations -- changes in the number or

structure of chromosomes

**Deletion -- removes all or part of chromosome

**Duplication -- extra copies of parts of a

chromosome

**Inversion --reverse the direction of part of the

chromosome

**Translocation -- part of one chromosome breaks

off and attaches to another chromosome

B. Frameshift mutation

1. Insertion -- one base is inserted

2. Deletion -- one base is deleted

**Can be much more dramatic --

changes the codon read

--Changes every amino acid

made after mutation

**Can alter the protein so much it

cannot function

17. SIGNIFICANCE OF

GENETIC MUTATIONS

A. most mutation are neutral = have no effect on phenotype

B. some can cause harm = disrupt normal biological function

by making wrong proteins

--genetic disorders

--cancer

C. SOURCE OF GENETIC VARIABILITY

--Produce new alleles

--Humans can make extra copies of genes in some

plants to increase their size = polyploid

18. GENETIC VARIATION

B4.4X

Genetic variation is essential to biodiversity and the stability

of a population.

Genetic variation is ensured by the formation of gametes and

their combination to form a zygote.

Opportunities for genetic variation also occur during cell

division when chromosomes exchange genetic material

causing permanent changes in DNA sequences of the

chromosomes.

Random mutations in DNA structure caused by the

environment are another source of genetic variation.

**READ 330 IN YOUR

BOOK AND CONDUCT THE

RESEARCH AND DECIDE

**Draw an example of each type of gene and chromosome

mutation. Explain how the effect of each.

19. RECOGNIZE THAT GENETIC

ENGINEERING TECHNIQUES

PROVIDE GREAT POTENTIAL AND

RESPONSIBILITIES. (B4.2H) (B4.R5B)

-- bacteria, plants, and animals are genetically engineered

(transgenic organisms)

20. TRANSGENIC

BACTERIA

1. Bacteria

A. recombinant DNA allows bacteria to be large groups for

the sole purpose of harvesting specific proteins

-- used to make insulin, human growth

hormone, and hepatitis B vaccine

B. “eat oil” and clean up toxic waste

C. make Nutrasweet

D. extract metals from mining

operations

21. TRANSGENIC

PLANTS

2. Plants

A. insert genes from insect toxins have been inserted into

cotton and soybean seeds to create pest resistant variants

B. use plants to create human proteins such as hormones,

clotting factor, and antibodies.

22. TRANSGENIC

ANIMALS

3. Animals

A. inserting growth hormone from cows has been used to increase the size of fish, cows, pigs, rabbits, and sheep

B. Cloning

C. Animal organs as transplant organs

D. Gene therapy – insertion of genetic material into human cells for the treatment of a disorder

o No ill effects have been detected yet from manipulating genes

o However the field is still very young it may possibly have health and ecological effects in the future

23. RECOMBINANT

DNA

Recombinant DNA B4.r5x

Recombinant DNA technology allows scientists in the

laboratory to combine genes from different sources,

sometimes different species, into a single DNA molecule.

This manipulation of genes using bacterial plasmids has

been used for many practical uses including the mass

production of chemicals and drugs.

D. EXPLAIN HOW RECOMBINANT DNA

TECHNOLOGY ALLOWS SCIENTISTS TO ANALYZE

THE STRUCTURE AND FUNCTION OF GENES.

(B4.R2I) (B4.R5A)

1. Recombinant DNA – contains DNA from two or more

different sources

a. restriction enzymes are used to cut specific

points in the DNA sequence.

b. then DNA ligase can be used to insert the DNA

segment into a plasmid (small piece of bacterial

DNA).

c. the plasmid then forces the bacteria to produce

the proteins created by that section of DNA

d. a gene is just a segment of DNA!!!

e. used to make insulin