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DNA & Heredity
Vocabulary
Fertilization-male and female reproductive
cells join
Dominant trait- the gene that shows
Recessive trait- the gene that doesn’t
show
Co-dominant trait- when both genes are
expressed
Incomplete dominance- when neither gene
is expressed they make an intermediate
Phenotype- the physical characteristics
Genotype- the actual genetic makeup
Homozygous- has 2 identical alleles for a particular
trait (TT or tt) (true breeding)
Heterozygous-has 2 different alleles for the same
trait (Tt) (hybrid)
Genetic engineering/gene splicing- direct changing
of the genes
Gene- the chemical factors that determine traits
Alleles-the different forms of a gene
Cloning-making an exact genetic copy of something
Pedigree- is your family line
Mutation- change in the DNA
Inheritance- passing on of something from parent to
offspring
Gregor Mendel
Austrian Monk
Did experiments on pea plants
He cross pollinated pea plants. To
see what would happen.
He wanted to know why you have
different kinds of pea’s
Medel based his experiments on these traits
When you mix these different trait you get
hybrids
After his first pollination he noticed that one of
the parents characteristic (traits or genes) were
not present
Segregation- This is the suggestion that
the alleles (dominant and recessive)
separate from each other.
Punnett Squares- this is a
way to estimate the
probability of
what will be the
result from the
cross of the
alleles
Independent assortment- states that genes for
different traits can segregate independently
during gamete formation
– This help to account for the many genetic variations
observed in plants and animals
Probability- can predict average outcomes of a
large number of events. However it can not
predict the precise outcome of an individual
event
Multiple Alleles- have more than 2 allele
possibilities in the population. Doesn’t mean that
a person can have more than 2 alleles. Ex.
(blood type)
Polygenic traits- traits controlled by two or more
genes. Ex. ( human skin color)
Why should we care?
About Mendel?
About DNA?
Disorders
Nondisjunction- when the chromosomes
don’t split from each other giving one cell
more than the other.
Autosomal- these are all of your
chromosomes except for your sex
chromosomes. You have 44 autosomal
chromosomes.
Down syndrome- produces mild to severe
mental retardation. (nondisjunction)
Sex – linked traits
Colorblindness- more common in males
Hemophilia- blood clotting also more common in
males
Duchenne Muscular Dystrophy- progressive
weakening and loss of skeletal muscle also more
common in males
Turners- happens in females only get one X they are
sterile (nondisjunction)
Klinefelter’s- happens in males they have an extra X
that interferes with meiosis prevents these
individuals from reproducing (nondisjunction)
Karyotypes / Pedigree
Karyotype- is a way to look at the actual
chromosomes.
Pedigree- show’s my
families traits for several
generations
Vocabulary
Nucleotide- A sugar, base and a
phosphate
Base pair- A-T, C-G
Codon- 3 bases in a row on the mRNA
strand
Anticodon- the 3 bases that are on the
tRNA
The finding of DNA
Fredrick Griffith- in 1928 found out that a heat killed
bacteria can transform a harmless strain into one that can
cause disease
Oswald Avery in 1944 figured out that genes are made of
DNA
Erwin Chargaff- figured out that Adenine paired Thymine,
and Cytosine paired with Guanine (Chargaff’s Rule)
Rosalind Franklin – in 1952 took x-ray photographs of DNA.
Watson and Crick – in 1953 were credited with the
discovery of the structure of DNA
Sydney Brenner- in 1960 found the existence of RNA
Walter Gilbert and Team- in 1977 found a way to read the
DNA sequence
2000 the human genome project- sequence all human DNA
DNA
DNA (Deoxyribonucleic Acids)- it is a
double helix shape
– Adenine, Thymine, Guanine, Cytosine -the 4
bases nucleic acids
– Adenine pairs with Thymine
– Guanine pairs with Cytosine
RNA (Ribonucleic Acids)- single stranded
– Instead of Thymine, it has Uracil
DNA replication
DNA molecule separates into
two strands, then produces
two new complimentary strands
following the rule of base pairing.
Each strand of the double helix
of DNA serves as a template,
or model, for the new strand.
Transcription
DNA is separated to be used as a
template to make an mRNA strand.
Enzymes are
used to split
the DNA
mRNA- messenger RNA. RNA molecule
that carries copies of base pairs. To help
with making protein.
tRNA- transfer RNA. Helps transfer amino
acids to the mRNA.
Amino Acid
rRNA- ribose RNA
it is inside the ribosome.
tRNA
mRNA
Protein synthesis/Translation
mRNA- is grabbed onto by a ribosome. So
that the ribosome can hold it in place for
the tRNA.
The tRNA then comes and hooks onto the
mRNA and bring the amino acid.
When a bunch of amino acids are hooked
together it makes something called a
polypeptide chain (protein).
Mutations
Mutation- are changes in the genetic
material.
Frameshift- These may change every
amino acid that follows the point of
mutation.
– these are additions or deletions of a base
nucleic acid.
Point mutations- this is when 1 to 2 base
nucleic acids are substituted so they
change which base it is.