Download Biological Diversity Section 3 Student Notes

October 06, 2011
2.2 Asexual and Sexual Reproduction
Homework:
p. 29 #1-3
p. 36 #1-6
Create a table that looks
like this:
Advantages
Disadvantages
Asexual
Reproduction
Sexual
Reproduction
Read pages 35-36 and fill
in your table.
Why is it an advantage for
some species to be able to
reproduce asexually and
sexually?
3.0 DNA is the Inherited Material
Responsible for Variation
What do DNA and a set of books or enclopedias have in common?
October 06, 2011
3.1 DNA - Transmitter of Genetic Code
DNA - Deoxyribonucleic Acid
- DNA is the molecule responsible for storing
all the information that makes us who we are
Oswald Avery
- All living things contain DNA
- The Genetic Code is made up of four
different chemicals: (G = guanine, C =
cytosine, A = adenine, T = thymine)
- The same genetic code (or language) is used
for all living things on earth
James Watson and
Francis Crick
3.1 DNA - Transmitter of Genetic Code
In most organisms, DNA is found in the nucleus of the cell and
it is highly organized.
An encyclopedia analogy is useful when describing how DNA is
organized:
DNA
DNA is written in the Genetic
Code which uses 4 different
chemicals (A, C, T, G)
Encyclopedias
Encyclopedias are written in
the English Language which
uses 26 letters
October 06, 2011
3.1 DNA - Transmitter of Genetic Code
DNA
The Human genome is
arranged into chromosomes.
Each cell contains 23 pairs
of chromosomes. (total = 46)
One set of chromosomes
came from each parent
Different organisms have
different numbers of
chromosomes (not related to the
Encyclopedias
Encyclopedias are arranged into
volumes (usually about 23)
different books)
A person can own two sets of
encyclopedias - the information
will mostly be the same in both
sets
complexity of the organism)
3.1 DNA - Transmitter of Genetic Code
DNA
Each chromosome is
divided into genes. Humans have
about 30,000 genes which works out to about
1,300 genes per chromosome
Because organisms have
two sets of chromosomes,
they also have a pair of
each gene.
Encyclopedias
Each volume (book) is divided
into sections
If you have two sets of
encyclopedias, you will have two
copies of the same information
October 06, 2011
3.1 DNA - Transmitter of Genetic Code
Encyclopedias
DNA
Organisms have two copies
of each gene which may be
the same or different.
Different versions of a gene
are called alleles
If you have two sets of
encylopedias, the information in
each, although similar, may be
slightly different.
3.1 DNA - Transmitter of Genetic Code
For example:
Widows
Peak
Widows
Peak
Type A
Blood
Type B
Blood
Brown
Eyes
Blue
Eyes
This chromosome has three
genes on it for hairline, blood
type, and eye colour.
You can see there are different
"versions" or alleles of each gene.
Every individual has a pair of
genes - they may be the same
alleles as in hairline here, or they
may be different alleles as in
blood type and eye colour
October 06, 2011
Homework: p.45 #2-4, 8, 10
3.2 Cell Division
Why do cells divide?
Cell
Division
Bean
Germination
Does growth mean the same thing for fish as it does
for bacteria?
October 06, 2011
3.2 Cell Division
46
There are 2 types of cell division:
Mitosis
Purpose: Growth & Repair
Daughter Cells: Identical to parent cells
"92"
46
46
3.2 Cell Division
46
There are 2 types of cell division:
Meiosis
"92"
Purpose: Produce gametes
Daughter Cells: Half the number of
chromosomes of the
parent cell
46
Gametes:
23
23
46
23
23
October 06, 2011
3.2 Cell Division
Organism
Number of
chromosomes in
a body cell
Number of
chromosomes in
a gamete
Number of
chromosomes in
a zygote
Number of pairs
of chromosomes
in a body cell
18
Cabbage
Black Bear
76
23
Human
Tomato
12
3.2 Cell Division
What is Cancer:
Cancer: Uncontrolled Cell Growth
Cancer
Cell Growth
Henrietta
Lacks
Homework: p.48 #1-3, 6, 7, 8
October 06, 2011
3.3 Patterns of Inheritance
The dobermann sub-species
was bred in 1890 by Karl
Friedrich Louis Dobermann
to help protect him while he
was collecting taxes.
Purebred German Pinscher
Purebred Beauceron
What does purebred mean?
What is a hybrid?
Dobermann Pinscher
3.3 Patterns of Inheritance
Purebred: An organism that consistently produces offspring
with the same characteristics
Purebred organisms are homozygous (they have the same alleles)
Ex. There are two alleles for the ability to
roll your tongue:
R = can roll your tongue
r = can't roll your tounge
Homozygous individuals would have either
two copies of the R allele (RR) or two
copies of the r allele (rr)
October 06, 2011
3.3 Patterns of Inheritance
Hybrid: An organism that is the result of a cross between two
different purebred parents.
Hybrid organisms are usually heterozygous (they have two
different alleles)
Ex. RR (homozygous mom)
x
rr (homozygous dad)
In sexual reproduction, offspring
receive one allele from each
parent (determined at random)
Rr (heterozygous offspring)
Do you think this person will be able to roll their tongue or not?
3.3 Patterns of Inheritance
Alleles may be considered 'dominant' or 'recessive'.
The dominant allele is represented by an upper case
letter and the recessive allele by a lower case letter.
Dominant Allele
Recessive Allele
Detached
Earlobes
in humans (E)
Attached
Earlobes
in humans (e)
White wool
in sheep (W)
Black wool
in sheep (w)
Purple pea
flowers (F)
White pea
flowers (f)
Would an individual with EE
have attached or detached ear
lobes?
Would a sheep with ww have
white or black wool?
Would a pea plant with Ff have
purple or white flowers?
Would an individual with Ee
have attached or detached ear
lobes?
October 06, 2011
3.3 Patterns of Inheritance
Every organism has two copies of each gene and only one is
passed on to their offspring.
If a purebred purple flowered pea plant (FF) is cross-polinated with a purebred white
flowered pea plant (ff), what will the offspring look like?
f f
F F
3.3 Patterns of Inheritance
What if two purple pea plants with different alleles (Ff) are cross-pollinated? What will
the offspring look like?
Ff
Ff
F or f
F or f
3 Combinations
are possible:
FF
Ff
ff
Are all of these
possibilities equally
likely?
October 06, 2011
3.3 Patterns of Inheritance
A punnett square is a tool that can be used to determine the
probabilities in the offspring.
In the cross to the right,
what fraction of the
offspring will have purple
flowers?
Male: Ff
Possible Male Gametes
What about white flowers?
What fraction would be
considered heterozygous?
Gametes
Possible Female Gametes
What fraction would be
homozygous?
Female: Ff
F
f
F
f
3.3 Patterns of Inheritance
Practice 2:
Practice 1:
Male: FF
Female: Ff
ff
Possible Male Gametes
Possible Female Gametes
Gametes
Gametes
FF
October 06, 2011
3.3 Patterns of Inheritance
Practice 3:
ff
More Practice:
Assuming white wool is dominant to black wool,
what will the offspring of a purebred white
sheep and a black sheep look like?
Ff
Make your own punnett square!
What percentage of the offspring
will be:
white?
Assuming smooth pea seeds are dominant to
wrinkled pea seeds, what would the seeds look
like if two "hybrid" pea plants are crossed?
purple?
homozygous?
heterozygous?
Homework: Patterns of Inheritance
Worksheet
3.3 Patterns of Inheritance
Not all traits follow patterns of
dominance & recessiveness:
Ex. Snapdragon flowers use something called
"incomplete dominance"
If it was a dominant / recessive
trait, the offspring would be either
red or white..... but
Incomplete dominance
results in blended traits