Homework for break
• Read Chapter 12 in textbook
• 2 Webquests
• Short Essay for second webquest typed.
Homework
•
Read beginning of chapter 12; complete
workbook section 12.1!
• Do Now:
1. How is meiosis different than mitosis?
2. What is the macromolecule involved in
storing information (be careful!)?
3. What are the monomers of this
polymer?
DNA and RNA
Genetics
Frederick Griffith 1928
Transformation - process in which one
strain of bacteria is changed by a gene or
genes from another strain of bacteria
Do Now
• Homework: workbook 12.2 w/ associated
reading; have workbook 12.1 out to
check
1. What did Griffith’s and Avery’s
experiments prove? Give a brief
paragraph explaining the importance of
their findings.
Avery and other scientists discovered
thatOswald
DNA is the nucleic
acid1944
that stores
Avery
and transmits the genetic information
from one generation of an organism to
• World
knows a molecule carries the
the next.
genetic information.
• Doesn’t know if the molecule is a:
protein, lipid, carbohydrate, RNA, or DNA
• Avery performs Griffith’s experiment
again with a twist.
Hershey-Chase Experiment
1952
• Good scientists are naturally skeptical.
• Hershey-Chase are testing to see if DNA
is the molecule that carries genetic
information.
• Bacteriophage - virus that infects
bacteria
Quiz
• Explain the importance of Griffith’s and
Avery’s experiments in determining the
molecule responsible for determining
genetic inheritance…
• Homework: Section Assessment 1 and 2
of chapter 12 (LL)
Hershey-Chase Experiment
DNA Structure
• Nucleotide monomer of
nucleic acids
made up of a 5carbon sugar, a
phosphate
group, and a
nitrogenous base
Sugar-Phosphate Backbone
and Chargaff’s Rule
• Simply states: If I
have a certain
number of
Cytosines I will
have about the
______ number
of Guanines.
Same with A’s
and T’s.
Rosalind Franklin 1950
X-Ray Diffraction
• Clues from
the X-Ray
– Coiled
(forming
Helix)
– Doublestranded
– Nitrogeneous
bases are in
the center
Watson & Crick
• Francis Crick – British physicist
• James Watson – American Biologist
– Building a 3D model of DNA
– Franklin’s X-Ray opened their eyes to the
Double Helix
• Watson and Crick’s model of DNA was
a double helix, in which two strands
were wound around each other.
Double Helix
Homework Study Guide
12-1 and 12-2
1. List the conclusions and how each of these
scientist got there:
– Griffith
– Avery
– Hershey and Chase
2. How did Watson and Crick’s model explain
why there are equal amounts of thymine and
adenine in DNA?
3. Why did Hershey and Chase grow viruses in
cultures that contained both radioactive
phosphorus and radioactive sulfur? What
might have happened if they only used one?
Prokaryote DNA
• Prokaryotes
– No Nucleus
– Most have one circular chromosome located in
the cytoplasm with some plasmids as well
– E.Coli (1.6μm diameter)
– 4,639,221 base pairs 1.6mm long
– Like packing 300m of rope in your backpack
Eukaryotes and DNA
• 1000 time more base pairs than bacterial
DNA
• Smallest human chromosome has
30million base pairs of DNA
• How do eukaryotes fit all that DNA in its
nucleus?
DNA to Chromosomes
• Vocab
– Chromatin - granular material
(uncondensed) within the nucleus; consists
of DNA tightly coiled around proteins
– Chromosomes – condensed chromatin
– Histone - globular protein molecule around
which DNA is tightly coiled in chromatin
DNA Replication
• During DNA replication, the DNA
molecule separates into two strands,
then produces two new complementary
strands following the rules of base
pairing. Each strand of the double helix of
DNA serves as a template, or model, for
the new strand.
Read 12-3
• Crossword Puzzle
1. Enzymes unwind
DNA
2. Enzymes split
“unzip” double helix
3. The enzyme, DNA
polymerase, finds
and attaches the
corresponding Nbase
4. Each “old” stand
serves as a
template and is
matched up with a
new stand of DNA
5. New helixes wind
back up.
DNA Replication
A–C–T–T–G–G–A–C
T–G–A–A–C–C–T-G
Homework 12-3 Study
Guide
• Quiz (5 min. – LL)
RNA
and
Protein Synthesis
• Codon - three-nucleotide sequence on
messenger RNA that codes for a single
amino acid
• Anticodon - group of three bases on a
tRNA molecule that are complementary
to an mRNA codon
Protein Synthesis
Two Main Parts
• Transcription
– Formation of a single
strand of
messenger RNA
from DNA in the
nucleus
• Translation
– Occurs on ribosomes
– Cell uses the
information on mRNA
to assemble amino
acids in the proper
order to form specific
proteins
Transcription
1. Occurs in nucleus
2. Enzymes unwind
DNA
3. Enzymes split
“unzip” double helix
4. RNA Polymerase
binds to promoter
sequence on DNA
5. RNA Polymerase
transcribes a single
strand of mRNA
mRNA Editing
before going to transcription
• Intron - intervening
sequence of DNA;
does not code for a
protein (not used)
• Exon - expressed
sequence of DNA;
codes for a protein
(used)
Translation
Translation
Genes and Proteins
• Most genes only have instructions for
assembling proteins.
• If that’s the case what do proteins have
to do with eye color, hair color or height?
Homework
•
Complete workbook section 12.3 and 12.4;
study for quiz (E Day)
• Do Now:
1. Discuss DNA Replication. How is it related to
RNA replication? List all the details you can
in sequential order!
2. What happens when there are errors in
“copying”? What are some of the ways we
can fix this? What happens if we don’t?
Mutations
• Mutation - change in a DNA sequence
that affects genetic information
• Two Main Types:
– Gene Mutation
• Mutation that causes a change in a single gene
– Chromosomal Mutation
• Mutation that causes a change in an entire
chromosome
Gene Mutations
• Point Mutation
(substitution)
– mutation that affects a
single nucleotide,
usually by substituting
one nucleotide for
another
• Frameshift Mutation
(insertion or deletion)
– mutation that shifts
the “reading” frame of
the genetic message
by inserting or
deleting a nucleotide
Chromosomal Mutations
• Chromosomal mutations involve
changes in whole chromosomes.
Homework: Check site!
Gene Regulation
Gene Regulation
• Prokaryote Gene Regulation
– Will often have one OPERATOR (regulatory
site) controlling the expression of more than
one gene. OPERON
• Eukaryote Gene Regulation
– Most eukaryotic genes are controlled
individually and have regulatory sequences
that are much more complex than those of
the lac operon
Gene Regulation
Vocab
• Promoter - region of DNA that indicates
to RNA polymerase where to bind to
make RNA
• Operon - group of genes operating
together
• Operator - region of chromosome within
an operon to which the repressor binds
when the operon is “turned off”
Lac Operon
(E. coli)
• Operator bound –
RNA polymerase
can’t transcribe
genetic
information (not
expressed)
• Operator free –
gene(s) expressed
Eukaryote Gene Regulation
Genes are regulated
in a variety of ways
by enhancer
sequences
DNA region about 30bp long
TATATAAA: help to align
RNA Polymerase
Gene Reg. and Development
• hox genes - series of
genes that controls
the organs and tissues
that develop in various
parts of an embryo
• Mutations affecting the
hox genes in the fruit
fly, Drosophila, for
example, can replace
the fly’s antennae with
a pair of legs growing
right out of its head!
1.
2.
3.
4.
5.
6.
7.
What is meant by term base pairing? How is base
pairing involved in DNA replication?
When a DNA molecule is replicated, how do the new
molecules relate to the original molecule?
What is the difference between introns and exons?
What is a codon? Anticodon? How do they relate?
Explain why controlling proteins in an organism
controls the organism’s traits.
Name two major types of mutations. What do they
have in common? How are they different? Give an
example of each.
The word transcribe means “to write out”, and the
word translate means “to express in another
language.” Review the meanings of transcription and
translation in genetics. How do the technical
meanings of these words relate to meanings of the
words in ordinary language?