Transcript Lesson Overview - Pottsgrove School District

Lesson Overview
12.1 Identifying the
Substance of Genes
Lesson Overview
Identifying the Substance of Genes
Griffith’s Experiments
Griffith isolated two different strains of bacteria.
Only one caused pneumonia.
Lesson Overview
Identifying the Substance of Genes
Griffith’s Experiments
When injecting mice with disease-causing bacteria, the mice
died.
When injecting mice with harmless bacteria, the mice stayed
healthy.
Lesson Overview
Identifying the Substance of Genes
Griffith’s Experiments
First, Griffith took the S strain, killed them, and then injected
the them into mice.
Mice survived, showing that it wasn’t a toxin the bacteria
produce.
Lesson Overview
Identifying the Substance of Genes
Griffith’s Experiments
In Griffith’s next experiment, he mixed the heat-killed S-strain
with harmless R strain and injected the mixture into mice.
The mice died.
Lesson Overview
Identifying the Substance of Genes
Transformation
Process called transformation - one type of bacteria is changed
into another.
Because transformed bacteria inherited ability to cause disease,
Griffith concluded the transforming factor was a gene.
Lesson Overview
Identifying the Substance of Genes
The Molecular Cause of Transformation
Avery destroyed proteins, lipids, carbohydrates, and RNA.
Transformation still occurred.
Lesson Overview
Identifying the Substance of Genes
The Molecular Cause of Transformation
Then destroyed DNA and transformation did not occur.
Therefore, DNA was the transforming factor.
Meant that DNA stores and transmits genetic
information.
Lesson Overview
Identifying the Substance of Genes
Bacteriophages
Bacteriophage - virus that infects bacteria
Lesson Overview
Identifying the Substance of Genes
The Hershey-Chase Experiment
Hershey and Chase studied a bacteriophage with a DNA core and a
protein coat.
Wanted to determine if the protein or DNA changed bacteria
Hershey and Chase grew viruses containing P-32 and S-35
Lesson Overview
Identifying the Substance of Genes
The Hershey-Chase Experiment
Bacteria contained P-32 , found in DNA.
Hershey and Chase confirmed Avery’s results - that DNA was the
genetic material found in genes.
Lesson Overview
Identifying the Substance of Genes
The Role of DNA
DNA can store, copy, and transmit genetic information
Lesson Overview
12.2 The Structure of DNA
Lesson Overview
Identifying the Substance of Genes
Nucleic Acids and Nucleotides
Located in nucleus.
Made up of nucleotides.
Three components: a 5-carbon sugar called deoxyribose, a
phosphate group, and a nitrogenous base.
Lesson Overview
Identifying the Substance of Genes
Nucleic Acids and Nucleotides
DNA has four nitrogenous bases: adenine, guanine, cytosine,
and thymine, or AGCT
Lesson Overview
Identifying the Substance of Genes
Chargaff’s Rules
Chargaff discovered the amount of
[A] and [T] bases are almost
equal. The same is true for
guanine [G] and cytosine [C].
- [A] = [T] and [G] = [C] is known
as “Chargaff’s rules.”
Lesson Overview
Identifying the Substance of Genes
Franklin’s X-Rays
Rosalind Franklin used X-ray
diffraction that showed:
- DNA has 2 strands twisted
around each other.
- The nitrogen bases are near
the center.
Lesson Overview
Identifying the Substance of Genes
The Work of Watson and Crick
Franklin’s X-ray pattern enabled
Watson and Crick to build a
model of DNA.
Built 3-D model of DNA in a
double helix
Lesson Overview
Identifying the Substance of Genes
Antiparallel Strands
DNA strands are “antiparallel”— they run
in opposite directions.
Lets nitrogenous bases join at center and
allows each strand to carry nucleotides.
Lesson Overview
Identifying the Substance of Genes
Hydrogen Bonding
Hydrogen bonds form between bases
and hold strands together.
Hydrogen bonds are weak and allow
strands to separate.
Lesson Overview
Identifying the Substance of Genes
Base Pairing
Fit between A–T and G–C
nucleotides called base
pairing.
EUKARYOTIC DNA REPLICATION
Step 1 – Helicase unzips the DNA molecule.
Step 2 – DNA Polymerase adds on complementary
nucleotides.
Step 3 – The lagging strand replicates in fragments instead
of continually like the leading strand.
Leading Strand
Lagging Strand
OKAZAKI FRAGMENTS
Step 4 –Enzyme ligase joins the fragments on lagging
strand.
Step 5 – As replication continues, the strands twist back
into helix.
TELOMERES
Are the tips of chromosomes make sure genes aren’t lost
during replication.
PROKARYOTIC DNA REPLICATION
Starts at single point,
and goes in 2
directions until the
chromosome is
copied.
PROKARYOTIC VS. EUKARYOTIC
DNA Replication Process [3D Animation] – Biology / Medicine Animations HD
https://www.youtube.com/watch?v=27TxKoFU2Nw
Lesson Overview
Fermentation
Lesson Overview
13.1 RNA
Lesson Overview
Fermentation
The Role of RNA
First step - copy DNA into RNA.
RNA, like DNA, is a nucleic acid made
of nucleotides.
RNA uses the base sequence copied
from DNA to make proteins.
Lesson Overview
Fermentation
Comparing RNA and DNA
Each nucleotide in both DNA and RNA is made up of a
5-carbon sugar, a phosphate group, and a nitrogenous
base.
Three differences between RNA and DNA:
(1) Sugar in RNA is ribose
(2) RNA is single-stranded.
(3) RNA contains uracil (U) instead of thymine (T).
Lesson Overview
Fermentation
Comparing RNA and DNA
The cell uses DNA “master plan” to prepare RNA
“blueprints.”
DNA stays in nucleus, while RNA goes to ribosomes.
Lesson Overview
Fermentation
Functions of RNA
RNA is like a disposable copy of a
segment of DNA, a working copy of a
single gene.
RNA assembes amino acids into
proteins.
Lesson Overview
Fermentation
Functions of RNA
Three main types of RNA:
messenger RNA, ribosomal RNA, and transfer RNA.
Lesson Overview
Fermentation
Messenger RNA
The RNA molecules that carry
instructions are known as
messenger RNA (mRNA)
Lesson Overview
Fermentation
Ribosomal RNA
Ribosomal RNA (rRNA) make up
ribosomes.
Lesson Overview
Fermentation
Transfer RNA
Transfer RNA (tRNA) transfers
amino acids to the ribosome
Lesson Overview
Fermentation
Making RNA - Transcription
Transcription – Turning DNA into RNA.
Lesson Overview
Fermentation
Transcription
In prokaryotes, RNA and
protein synthesis occurs in the
cytoplasm.
In eukaryotes, RNA is produced
in the nucleus and moves to
the cytoplasm to produce
proteins.
Lesson Overview
Fermentation
Transcription
Requires RNA polymerase, which separates DNA strands to
assemble complementary strand of RNA.
Lesson Overview
Fermentation
Promoters
RNA polymerase binds to
promoters.
Promoters show RNA
polymerase where to begin
making RNA.
Similar signals cause
transcription to stop.
Lesson Overview
Fermentation
RNA Editing
Parts of RNA are cut out and stay in
the nucleus are called introns.
The remaining pieces, known as
exons, are joined together into the
final mRNA, which exits the nucleus.
Lesson Overview
Ribosomes and Protein Synthesis
Lesson Overview
13.2 Ribosomes and
Protein Synthesis
Lesson Overview
Ribosomes and Protein Synthesis
The Genetic Code
First step - transcribe DNA to RNA.
Contains code for making proteins.
The genetic code is read three “base
letters” at a time and corresponds to a
single amino acid.
Lesson Overview
Ribosomes and Protein Synthesis
The Genetic Code
Proteins are made by joining amino acids together into long
chains, called polypeptides.
There are about 20 amino acids.
Lesson Overview
Ribosomes and Protein Synthesis
The Genetic Code
The type and order of amino acids
determine the properties of proteins.
Order of amino acids affects the shape
of the protein, which determines its
function.
Lesson Overview
Ribosomes and Protein Synthesis
The Genetic Code
Each three-letter “word” in mRNA is known as a codon.
A codon specifies a single amino acid.
Lesson Overview
Ribosomes and Protein Synthesis
Start and Stop Codons
The “start” codon AUG begins
protein synthesis.
Then mRNA is read, three bases
at a time, until it reaches a
“stop” codon, which ends
translation.
Lesson Overview
Ribosomes and Protein Synthesis
Translation
The decoding of mRNA into amino acids is
called translation.
Lesson Overview
Ribosomes and Protein Synthesis
Steps in Translation
mRNA is transcribed in the nucleus and then translated in the
cytoplasm.
Lesson Overview
Ribosomes and Protein Synthesis
Steps in Translation
Translation begins when a
ribosome attaches to mRNA.
As the ribosome reads mRNA,
it directs tRNA to bring amino
acid.
Lesson Overview
Ribosomes and Protein Synthesis
Steps in Translation
Each tRNA molecule carries
one amino acid.
Each tRNA has three unpaired
bases, called the anticodon —
which compliment one mRNA
codon.
Lesson Overview
Ribosomes and Protein Synthesis
Steps in Translation
Peptide bonds form between amino
acids
At the same time, the bond holding
tRNA to its amino acid is broken.
Lesson Overview
Ribosomes and Protein Synthesis
Steps in Translation
The polypeptide chain grows until
the ribosome reaches a “stop”
codon, which completes
translation.
Lesson Overview
Ribosomes and Protein Synthesis
The Roles of tRNA and rRNA in
Translation
rRNA holds ribosomal proteins in place.
Lesson Overview
Ribosomes and Protein Synthesis
The Molecular Basis of Heredity
Genes contain instructions for assembling proteins.
Lesson Overview
Ribosomes and Protein Synthesis
The Molecular Basis of Heredity
Gene expression - the way DNA, RNA, and proteins put genetic
information into action in living cells.
Lesson Overview
Ribosomes and Protein Synthesis
The Molecular Basis of Heredity
There is a near-universal nature in the genetic code.
Although some organisms show slight variations in the amino acids
assigned to particular codons, the code is always read three bases
at a time and in the same direction.
Despite their enormous diversity in form and function, living
organisms display remarkable unity at life’s most basic level, the
molecular biology of the gene.
Lesson Overview
Ribosomes and Protein Synthesis
Lesson Overview
13.3 Mutations
Lesson Overview
Ribosomes and Protein Synthesis
Types of Mutations
Cells can make mistakes, called mutations
Lesson Overview
Ribosomes and Protein Synthesis
Types of Mutations
All mutations fall into two basic
categories:
Gene mutations - changes in a
single gene
Chromosomal mutations changes in whole chromosomes.
Lesson Overview
Ribosomes and Protein Synthesis
Gene Mutations
Point mutations - changes in
one or a few nucleotides.
Changes can be passed on
to every cell that develops
from the original one.
Lesson Overview
Ribosomes and Protein Synthesis
Gene Mutations
Point mutations include substitutions, insertions, and
deletions.
Lesson Overview
Ribosomes and Protein Synthesis
Substitutions
In a substitution, one base is changed to a different base.
Usually affect a single amino acid
Lesson Overview
Ribosomes and Protein Synthesis
Insertions and Deletions
Insertions and deletions are mutations in which one base is
inserted or removed.
Called frameshift mutations because they shift the “reading
frame” of the genetic message.
Lesson Overview
Ribosomes and Protein Synthesis
Chromosomal Mutations
Chromosomal mutations involve changes in the number or
structure of chromosomes.
Four types: deletion, duplication, inversion, and translocation.
Lesson Overview
Ribosomes and Protein Synthesis
Chromosomal Mutations
Deletion involves the loss of all or part of a chromosome.
Lesson Overview
Ribosomes and Protein Synthesis
Chromosomal Mutations
Duplication produces an extra copy of all or part of a
chromosome.
Lesson Overview
Ribosomes and Protein Synthesis
Chromosomal Mutations
Inversion reverses the direction of parts of a chromosome.
Lesson Overview
Ribosomes and Protein Synthesis
Chromosomal Mutations
Translocation occurs when part of one chromosome breaks off
and attaches to another.
Lesson Overview
Ribosomes and Protein Synthesis
Effects of Mutations
Genetic material can be altered by
natural or artificial means.
Resulting mutations may or may not
affect an organism, most do not.
Some mutations that affect individual
organisms can also affect a species or
even an entire ecosystem.
Lesson Overview
Ribosomes and Protein Synthesis
Effects of Mutations
Many mutations are produced by
errors in genetic processes.
An incorrect base is inserted
roughly once in every 10 million
bases.
Small changes can accumulate
over time.
Lesson Overview
Mutagens
Ribosomes and Protein Synthesis
Some mutations arise from
mutagens - chemical or physical
agents in the environment.
Chemical mutagens include
certain pesticides, plant alkaloids,
tobacco smoke, and
environmental pollutants.
Physical mutagens include forms
of electromagnetic radiation, such
as X-rays and UV light. Stress
can also be a factor.
Lesson Overview
Ribosomes and Protein Synthesis
Harmful Effects
The most harmful mutations dramatically change protein
structure or gene activity.
Example: Sickle Cell Disease
Lesson Overview
Ribosomes and Protein Synthesis
Beneficial Effects
Some mutations can be highly advantageous to an organism
or species.
Example: Pesticide Resistance and Polyploidy