Basic Genetics

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22 Οκτ 2013 (πριν από 3 χρόνια και 7 μήνες)

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Genetics:

Study of Heredity

Aim:

What is Genetics?

http://www.youtube.com/watch?v=eOvMNOMRRm8

Sexual Reproduction:


Two parents


Half of the genetic information is
received from one parent, half from
the other.


Variation


Evolution

Asexual Reproduction:


One parent


Offspring is identical to parent.


Clones
-

identical genetic copies.


Genetics:


Gregor Mendel
-

1800’s


“Father of Genetics”


Pea plants: easy to grow


Contrasting traits


Easily self and cross pollinate.


From his studies, Mendel arrived at
conclusions that are the basis for genetics
today!

Additional Vocabulary


Genetics:

Study of heredity


Heredity:

Passing of genetic information
from an organism to it’s offspring.


Genes:

units of heredity


Determines traits/ characteristics an
offspring will have.


Located on chromosomes.


For each trait
-
> minimum of 2 genes. One
from mom, one from dad.



There are many genes located on a
Chromosome.


Genes

Hereditary Information:


DNA
-

deoxyribonucleic acid


Organic (C, H, O, N, P).


Double stranded


Organized in the form of genes


located on the
chromosomes.

Hereditary Information:cont.


Homologous chromosomes
-

are same size
and shape (one from each parent)


This allows for crossing over and variation to
occur.




http://www.youtube.com/watch?v=lJzZ7p
-
47P8

Genotype vs. Phenotype:

Gen
otype
-

gen
es


Ex: B,b,S,s


Ph
enotype
-
Ph
ysical
appearance


Ex: Fur Color, Fur
Length

http://www.youtube.com/watch?v=jHWJqzlHl3w

Genetic Recombination:


Sperm and egg combine to form a
new cell.


New cell (offspring) has a complete
set of genetic information (DNA).
Each offspring is unique.


The Genetic Code:



Structure of DNA
was discovered by 2
scientists:


1953 James Watson
and Francis Crick


Created a model
known as the
Double Helix


a
twisted ladder.



What is the structure of DNA?


Structure of DNA


Long chain of repeating units ( polymer) called
nucleotides.


A nucleotide unit contains:

1. phosphate group O

2. deoxyribose (sugar)

3. nitrogenous base:


A
-

adenine


T
-

thymine


C
-

cytosine


G
-

guanine

Structure of DNA

One Strand of DNA


The backbone
of the molecule
is alternating
phosphate

and
deoxyribose
, a
sugar, parts.


The teeth are
nitrogenous

bases
.

phosphate

deoxyribose

bases

Two Stranded DNA


Remember,
DNA has two
strands that fit
together
something like a
zipper.

Types of nitrogen bases


A= adenine


G= guanine


C= cytosine


T= thymine


Structure of a Double Helix


Sides of the “ladder” are
alternating phosphate group
and deoxyribose sugar.


“rungs” of the ladder are made
of 2 nitrogenous bases.


Specific pairings:


There is a weak Hydrogen
bond

Between the base pairs.


Structure as a double helix


When a cell goes through
mitosis(cell division) the
DNA must also make a
copy of itself.

DNA by the numbers


Each cell has about 2
m of DNA.


The average human
has 75 trillion cells.


The average human
has enough DNA to
go from the earth to
the sun more than
400 times.


DNA has a diameter
of only 0.000000002
m.

The earth is 150 billion m

or 93 million miles from

the sun.

Aim:

How does DNA replicate?

Do Now:

Please answer the questions on
the handout found on the front desk, omit
questions 5
-
7.

G
enetics
C
an


T
ell
A
ll

G
-
Guanine

C
-
Cytosine

T
-
Thymine

A
-
Adenine

Base Pairing


Which bases always
match up?


A
-
T


G
-
C


Adenine always binds
with Thymine


Cytosine always binds
with Guanine

Steps of Replication:

1.

DNA unwinds

2. DNA unzips

3. Old strands become
templates for new
strands

4. Result
-

2 identical DNA
molecules


Characteristics of a Double
Helix


Proteins and Cell Functioning:


Proteins
-

long chains formed from
20 kinds of amino acids.


Sequence(order) of the amino acids
influences the shape of the
molecule.


Proteins include: enzymes, insulin,
eye color, and skin color.



DNA
-

Protein Connection:



Genes contain coded information.


This information is used to make
proteins that are required for it’s
function and structure.


Ribosomes construct proteins based on
the cell’s DNA code (combo of A, C, T,
G’s).


Parent and offspring produce similar
traits that is why there is resemblance
between them. They produce similar
proteins.

Aim: How does protein synthesis
Work?

Protein Synthesis:


The building of protein
molecules.


Synthesizing protein from
DNA.


Proteins are chains of amino
acids.


Steps:


Begins in the nucleus with DNA.


DNA code is read by a “ messenger
molecule” messenger RNA; ;


mRNA.


“messenger molecule: travels into
the cytoplasm of the cell to the
ribosome.


Steps cont.:


With the help of “transfer molecules”
tRNA amino acids move to the
ribosomes to make proteins.


The ribosomes “reads” the code and a
chain of amino acids is produced
forming a protein.


***Protein structure is determined by
DNA***



RNA:


Ribonucleic Acid


Single stranded


Nitrogenous bases


A
-

adenine


U
-

uracil


C
-

cystosine


G
-

guanine

Types of RNA



Messenger RNA (mRNA)

Copies code from DNA

Brings to ribosome


Transfer RNA (tRNA)

Brings amino acids to ribosome for
protein assembly


Mutations:

Alteration of DNA sequence.

Causes a change in code carried for by
the gene.

Random, but can be increased because
of chemicals, radiation.


Aim: What are different genetic
mutations?


Do Now: Please complete the handout on
the front desk.

Different Types of Mutations:


Original DNA Template
C A A T G C T A C


1.
Substitution:

one base pair for another.


C A A C G C T A C


2.
Deletion:
missing a base.




C A A T O C T A C


3.
Addition:

adding an extra base




C A A T A G C T A C


4.
Inversion:

bases are rearranged.



C A G A T C T A C





Causes of Mutations



Environmental Conditions

can affect how
genes are expressed.


Ex. Himalayan rabbit


Warmer body temperature


white fur


Colder body temperature


black fur


** Identical twins
-

separated
-

different
personalities


Chemicals, hormones can activate a gene,
causing certain proteins to be produced.

Genetic Engineering


Used to alter instructions in organisms.


Produce more desirable traits.

Selective Breeding:



Produces animals and plants
with desirable traits.


Horse & donkey= mule.
(outbreeding)


Ex. Larger, juicier fruits…


Pure dog, pure cat.
(inbreeding)

Inbreeding/ Outbreeding

Breeding continued:


** In sexually reproducing
organisms


only mutations found
on sex cells can be inherited by
the offspring.


Mutations occurring in body cells
will only affect that organism.

DNA and Individuality:


The order of the nitrogenous base pairs,
A,T,C,G’s are what makes each person an
individual and unique. This is because the order
allows for certain proteins to be produced.


In an organism every cell contains the same
genetic code.


However, each cell is different: hair cells, skin
cells, liver cells, stomach cells.

Gene Expression.


Each cell only uses some of the
genetic information from the
chromosomes.


Certain parts of the chromosomes
get “turned on” or “turned off.”

Gene Manipulation:


Altering genes using enzymes


By manipulating the DNA in plant
cells or animal cells; favorable
offspring can be produced


Produce bacteria that can be
beneficial.



Steps:


Cut DNA segment with enzymes


This segment can be spliced (moved) and
attached to DNA of a new organism.


New organism will make the protein coded
for by DNA code.

Gene Manipulation

Biotechnology:



Apply technology to biology.


Applications of Biotechnology:


By using gene therapy and applying
it to modern medicine scientists
may:


Produce hormones, enzymes and
other body chemicals.


Provide at a low cost.


Provide a purer form.