Download Characteristics of DNA

Warm-Up: Find the 6 differences between the two
pictures.
Source: http://www.slylockfox.com/arcade/6diff/index.html
The answers are …
Answers: Fish gill, tree stump, cat’s foot, dog’s mouth, bird’s beak, dog’s ear
Source: http://www.slylockfox.com/arcade/6diff/index.html
Objective
SWBAT explain why variations in nitrogenous base
sequences aid in the distinctiveness of an individual.
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Agenda
1.
2.
3.
4.
5.
6.
7.
DNA Paper Model
OJ Simpson Documentary
Genes
Identifying Characteristics of DNA
Extract Your Own DNA
OJ Simpson Documentary
Exit Slip
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
DNA Paper Model
OJ Simpson Documentary
Analysis Questions
1. Where does OJ claim that he was when the
murder was committed?
2. What was some evidence that was found at the
crime scene?
3. What did the forensic evidence show with Ron
Goldman?
4. What did the detective find when they arrived at
OJ Simpson’s house?
5. Why was OJ Simpson the prime suspect?
6. What did detectives notice when OJ Simpson
arrived back from Chicago?
Genes – Cellular Blueprints
A gene is a series of nucleotides
that codes for a certain
polypeptide (protein).
Each gene has at least
– Promoter region
– Initiation or start site
– Coding region
– Termination site
Eukaryotic genes can be as large
as 100,000 base pairs.
– Introns are non-coding
regions, usually spliced out
of created proteins
– Exons are coding regions
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Chromosomes – DNA Packaging
DNA is not floating loose inside the nucleus – most of
the time it is wrapped tightly around special proteins
called histones in structures called chromosomes.
There are two special chromosomes known as X and Y
which determine the sex of an individual. Almost all
individuals have two of these chromosomes.
An XX combination is a female
An XY combination is a male
A YY combination is impossible
All other chromosomes – those which do not determine
sex – are known as autosomes.
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Chromosomes – DNA Packaging
Almost all human cells are diploid – each of our 23
chromosomes come in pairs. One half of each pair
comes from the mother’s haploid egg (containing only
one copy of each chromosome); the other half comes
from the father’s haploid sperm.
The two chromosomes in each pair are called
homologous chromosomes because they each carry
similar genes controlling the same inherited
characteristics.
The prefix homo means ‘same’ or ‘similar’ – what other
scientific terms use it?
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Sexual Reproduction
Two parents give rise to
offspring that have unique
combinations of genes
inherited from the two
parents.
Each chromosome pair is
distinct and different and
contains different genes.
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Sexual Reproduction
Each of the two members
of a chromosome pair can
have slight differences in
the DNA sequences of the
genes it contains.
Different versions of the
sequence in the same
gene are called alleles.
The pair of alleles inherited
from your parents is called
a genotype.
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Sexual Reproduction
If an individual has
inherited the same gene
sequences from mom and
dad, they are
homozygous for those
alleles. If they inherit
different sequences, they
are heterozygous.
Which of these offspring
squares are homozygous
and which are
heterozygous?
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
• Heterozygote: individual
having two different alleles
at a genetic location
• Homozygote: individual
having two copies of the
same allele at a genetic
location
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved.
www.CrosscuttingConcepts.com
Everyone’s DNA has the same basic
makeup
• It’s the sequence of the base pairs that
makes us different!
• Therefore we can USE that sequence to
identify a person!
• However, there are MILLIONS of base
pairs, so scientists use a shorter method,
they analyze repeating sequences
(Tandem Repeating Sequences)
OJ Simpson Documentary
7. What was a key discovery for police on Simpson?
8. What happened when there was a warrant for
Simpson’s arrest?
9. Why was the Bronco a key crime scene?
10. What evidence did police dismiss or ignore?
11. Why do some think that Simpson should have
had more wounds/bruises?
12. Where did Simpson say the cuts came from?
13. What did the fingernail evidence suggest?
Exit Slip
October 7, 2014
1. Get out a mobile device or use one of
the computers and go to
m.socrative.com. You can also use one of
the iPads that has the Socrative app.
2. When prompted, enter 417101 for the
room number.
QUESTION: How does the nitrogen base
structure provide an identifying
characteristic to DNA?