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Chapter 8 - Heredity
• Heredity – is the passing of traits from parent to offspring.
• We call these “inherited traits”.
Inherited Traits
• Living things inherit many traits, or characteristics from their parents.
• Recall that _________, determine the inherited traits of an organism.
• Traits are determined by the genes you receive from your parents.
Genotype vs. Phenotype
• Genotype – “genetic makeup” of an organism.
• Phenotype –– the way an organism looks and behaves as a result of its genotype ----“physical makeup”.
• Genotype DETERMINES phenotype
Chromosomes• Genes are located on structures called
chromosomes.
• Cells of different kinds of organisms contain a different number of chromosomes.
• A human baby receives ______ chromosomes from its mother, and ______ from its father. Human body cells contain _______ chromosomes.
• Each pair of chromosomes are given a number from 1 to 23.
• Genes that determine a specific trait are in matching locations on paired ---“homologous” chromosomes.
Check List
• 1) _________ is the passing on of traits from parents to offspring.
• 2) A trait is contained in a ___________?• 3) What is the difference in genotype and
phenotype?• 4) How many chromosomes are in the human
body cell? How many from dad and mom?• 5) What are homologous chromosomes?
• Traits are controlled by a single gene.• An example of a gene is one that causes
earlobes to be attached to the head & another form that causes earlobes to be free from the head.
• Allele – different forms of a trait that make up a gene pair.– “alternate forms of the same
gene”
• Alleles may be either dominant or recessive for a particular trait.
Dominant vs Recessive Alleles
• Dominant allele – is one that is expressed when two different alleles are inherited.
• Recessive allele – is not expressed unless an organism inherits two copies of it.
Identifying Genotype and Phenotype
• Each pair of genes is part of an individual’s genotype (Ff, Bb, Gg, etc)
• Genotype identifies which alleles have been passed on to an organism.
• Capital letter – dominant• Lowercase letter – recessive
• Offspring receive two copies of each gene – one from each parent.
• 3 possible genotypes: FF, Ff, ff.
• Homozygous genotype - is made up of two dominant or two recessive alleles “the same”– Ex: FF or ff
• Heterozygous genotype - is made up of one dominant and one recessive allele “not the same”– Ex: Ff
Punnett Square
• Punnett Square – is a tool used to predict the results when two organisms mate.
• Used to calculate the probability of genotypes and phenotypes in offspring.
Check List • 1) What is the passing on of traits from parent to
offspring called?• 2) What is an organism’s genotype?• 3)An organism’s expressed traits make up its
____________?• 4) How many total chromosomes are their in a
human cell? How many pairs?• 5) _________ is two different forms of the same
gene.• 6) An allele can be either ______________ or
___________?
Father of Genetics • Gregor Mendel – is considered
the “father” of genetics. • First experimented with pea
plants in 1856. • He was a Austrian monk who
was fascinated with crossbreeding plants.
• First to develop punnett square to predict probabilities.
Advances in Genetics • Genetic Engineering – where scientist alter the
DNA of an organism to benefit.• 3 advantages of genetic engineering:– 1) Gene transfer (out with the bad in with the good)– 2) Genetically engineered plants– 3) Genetically engineered animals
Chapter 8 - Heredity
• Heredity - ____________________________
• ____________ are passed on to future generations
Inherited Traits
• Recall that _________, determine the traits of an organism.
• Traits are determined by the genes you receive from your parents.
• Genotype – __________________________________________________________________________
• Phenotype – __________________________________________________________________________
• Genotype DETERMINES phenotype
Chromosomes• 23 pairs of
chromosomes in each cell = __________ total
• Each pair has a chromosome from a mom and a dad.
• On each chromosome is an alternating ___________.
Chapter 8 Check List• 1) _____________ -is the process of passing traits from
parents to offspring.• 2) The genetic makeup or genes of an organism is called its
_________________.• 3) _________ determines the inherited traits of an organism. • 4) ______________ - is the way an organism looks and
behaves –“expressed or physical makeup”• 5) More complex organisms generally contain ________
chromosomes.• 6) Genes code for certain _____________.• 7) Inherited traits means we get our characteristics from our
______________. If we have 2 parents, there is ______________ in the offspring.
• 8) Above in #7, what type of reproduction has been involved?
Section 2
Chromosomes• Genes are located on structures called
chromosomes.
• Cells of different kinds of organisms contain a different number of chromosomes.
• Traits are controlled by a single gene.• An example of a gene is one that causes
earlobes to be attached to the head & another form that causes earlobes to be free from the head.
• Allele - _____________________________________
• Alleles can be either _______________ or _______________.
• Dominant Allele - _____________________________________
• Recessive Allele - _____________________________________
• Each pair of genes is part of an organism’s _________________. (ex: Ff, Dd, Tt)
• Genotype shows which alleles have been passed on.
• Capital Letter = ___________ allele • Lowercase Letter = _________ allele
• Offspring receive two copies of each gene – one from each parent.
• 3 possible genotypes:_______, _______, ______
• Homozygous genotype -______________________________________– Ex:
• Heterozygous genotype -_______________________________________– Ex:
Section 3
• Genotype vs Phenotype• Tt vs Tall• Homozygous vs Heterozygous • Dominant vs. Recessive • 3 genotypes
Punnett Square
• Punnett Square –____________________________________.
• Used to calculate the _________ of genotypes and phenotypes in offspring.
Task 1
• Draw a punnett square when a heterozygous parent for tallness mates with a homozygous parent for shortness. ( use T and t ).
Task 2
• Draw out a punnett square for two organisms that mate: one is Heterozygous for being athletic, and the other is homozygous recessive for being athletic (Use A or a)
Task 3
• A male eastern fox squirrel is notorious for mating in the winter months and for finding a mate who is always homozygous dominant. If a male eastern fox squirrel is homozygous for being slow and finds a mate draw a punnett square (F=fast; f=slow) and predict these:– What is the probability of the offspring being fast?– What is the probability of the offspring being slow?– What % will be homozygous?– What % will be heterozygous?
Section 3 cont.
Father of Genetics • Gregor Mendel –
______________________. • First experimented with pea
plants in 1856. • Used the ___________________
in his studies.
Advances in Genetics • Genetic Engineering –
___________________________________________________________.
• 2 advantages of genetic engineering:– 1)– 2)