The Central Dogma of Biology - Mrs. Frostmfrost.buchananschools.com/uploads/8/7/0/4/8704278/... ·...
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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