Genetics

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Genetics

• Genetics science of hereditary, how traits are
  passed from one generation to the next
• Inherited examples include Cystic fibrosis, skin
  eye color, sickle cell disease

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Gregor Mendel

• Father of Genetics - (1860s) discovered that
  the fundamental principles of genetics by
  breeding pea plants

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I. Mendels Principles.. discovered
that inheritance follows rules of chance

• A. Law of Dominance
• The allele of a pair that is
• expressed is called dominant
• (strongest) while the allele that
• is not expressed (hidden) when
• present with another is called
• recessive.
• B. Law of Segregation and Recombination genetic
  recombination
• When the male gamete unites with the female
  gamete to form a zygote, alleles recombine and
  new combinations are formed.
•  

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 C. Crossing Over bringing about variation!

• when the chromosomes come together in the
  beginning of meiosis, the arms of the chromosomes
  may twist around each other, break, and rejoin
  other chromosomes, thus creating linked genes and
  increasing the genetic possibilities of the
  offspring.

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D. Terms to know

• Homozygous- contains 2 identical alleles for the
  same trait, (pure gene)
• Heterozygous- contains 2 different alleles for
  the same trait, (hybrid)

• Allele
• Alternate forms or versions of a gene.
• Slightly different DNA codes and occur at the
  same location on homologous chromosomes

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Dominant allele

• The version of the gene that is expressed
  (observed) when both alleles are present.
• Symbolized with a capital letter Ex A

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Recessive allele

• The version of the gene that is not expressed
  (not observed) when both alleles are present.
• Symbolized with a lower case letter Ex a

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D. Terms to know

• Phenotype- physical characteristics are
  observable
• Genotype- Genetic combinations
• Example
• 1. tall pea plant TT tall (homozygous
  dominant)
• 2. dwarf pea plant tt dwarf (homozygous
  recessive)
• 3. tall pea plant Tt tall (heterozygous)

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E. Punnett square

• A Punnett square is used to show the possible
  combinations of gametes

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Mendels Pea plants
Genotype -vs- Phenotype TT
tall pea plant (homozygous dominant) Tt
tall pea plant (heterozygous dominant)
tt dwarf pea plant (homozygous
recessive)
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Practice Mendels Pea Plants tall (TT)
vs. dwarf (tt) pea plants
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F. The Gene Chromosome Model

• Hereditary information is contained in genes,
  which are composed of DNA, located in the
  chromosomes of each cell.
• Chromosomes are found in the nucleus of each cell.

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G. Gene Chromosome Theory

• Genes exist at definite locations in linear
  sequence on a chromosome and are found in
  homologous pairs.
• Chromosome? GENES ? DNA ? alleles? traits

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• Accounts for the hereditary differences Mendel
  observed.
• Genes are segments of DNA that contain
  instructions to make proteins.
• Each gene carries a separate piece of
  information. An inherited trait of an individual
  can be determined by one gene, but is usually
  determined by the interactions of many different
  genes

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Regents Practice Question. Which chromosome pair
below best illustrates the gene-chromosome theory?
4 - You Are Correct!The gene-chromosome theory
states that genes are segments of DNA located on
chromosomes and are found in homologous pairs.
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Bellwork turn to your table partner and discuss
the questions below..

• 1. What organelle is known as the control
  center of the cell?
• 2. What structures are found in the nucleus?
• 3. What are located on chromosomes?
• 4. What are genes composed of?

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DNA The Intro Clip
All ABOUT DNA
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I. DNA Structure

• A. Building Blocks
• 1. Nucleic Acids! (NUCLEOTIDES)
• 2. also known as subunits
• B. Nucleic acids- (4 of them)

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C. DNA Shape

• 1. Each nucleic (acid) is made of 3 parts
• a. Sugar (Deoxyribose)
• b. Phosphate
• c. 1 of 4 Nitrogenous Bases
• A adenine
• T thymine
• C cytosine
• G guanine

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C. DNA Shape

• DNA IS DOUBLE STRANDED
• STRANDS TWIST TO FORM DOUBLE- HELIX
• NITROGEN BASES BIND TOGETHER TO MAKE TWO STRANDS
• A always binds with T
• G always binds with C
• All Teachers
• Go Crazy
• THIS IS CALLED THE
• BASE-PAIR RULE!

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Base Pair Ruling
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DNA Structure
G
G
T
A
C
G
C
C
T
-----C
-----C
-----A
-----T
-----G
-----C
-----G
-----G
-----A

• Lets Practice!
• One strand of DNA has the sequence you see.
• What is the complimentary strands sequence???

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Replication The Video Clip (102)

• http//www.youtube.com/watch?vz685FFqmrpo

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II. DNA Replication (copying)
CLICK HERE FOR DEMO

• A. When does DNA need to be copied????
• 1. During any cell division! (mitosis and
  meiosis)
• B. First, two strands are unzipped
• C. Second, enzymes bring new subunits to these
  strands (templates)
• D. Third, you end up with 2 identical double
  helices
• E. DNA acts as a PATTERN or TEMPLATE to make
  copies of itself!
• CLICK HERE FOR DEMO 2

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DNA Replication Diagram
Parent Strands
New complimentary strands
Free Floating Nucleotides
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Replication Practice- Step 1 Unzip
G
G
T
A
C
G
C
C
T
-----C
-----C
-----A
-----T
-----G
-----C
-----G
-----G
-----A
G
G
T
A
C
G
C
C
T
C
C
A
T
G
C
G
G
A
Enzymes UNZIP
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Replication Practice- Step 2 Add Subunits using
Base-Pair Rule
G
G
T
A
C
G
C
C
T
C
C
A
T
G
C
G
G
A
----C
----C
----A
----T
----G
----C
----G
----G
----A
G----
G----
T----
A----
C----
G----
C----
C----
T----
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THE DNA RAP!!!!

• http//www.youtube.com/watch?vd1UPf7lXeO8