GeneticsWednesday/Thursday 1/7-1/8/2015

Agenda: Welcome Back!!

Notes: Intro to Genetics Activity: Brain Pop and Worksheet Activity: Genetic Terms Review Activity: Monster Genetics (due in class)

Homework/Class Work:1. Monster Genetics due Today for 50 Points

(Grade Book)2. Homework: Genetics Practice Problems

worksheet due Friday 1/9/2015 for 10 Points

1. Chimp’s & human’s DNA are 98% identical.

2. The father determines the sex of the offspring.

3. A genetic blood disorder can make your skin look blue.

4. A person may transmit characteristics to their offspring which he/she do not show themselves.

5. Geneticists have created a potato that can self destruct.6. We share 40-50% of our DNA with cabbages7. Scientists estimate that 99.9 percent of the DNA of most

humans is identical.8. Each parent contributes half of their child’s genetic make-up.9. Henrietta Lacks was a woman with a mutation who had

immortal cells, who later died of cervical cancer (kidney injury)

10. Humans share 50% of their DNA with bananas.

THE FIELD OF BIOLOGY DEVOTED TO UNDERSTANDING HOW CHARACTERISTICS ARE PASSED FROM PARENT TO OFFSPRING.

Q3 WK1 D1

Genetics:

Jan. 7, 2013

GREGOR MENDEL (1823 – 1884)

• AUSTRIAN MONK WHO STUDIED MATH & STATISTICS.

• HE BECAME KNOWN AS THE “FATHER OF GENETICS”.

• HE CONDUCTED EXPERIMENTS ON PEA PLANTS.

MENDEL’S PEA PLANT EXPERIEMENTS

• He observed 7 characteristics of pea plants • each characteristic had only 2 contrasting traits.

- height- flower position along the stem- pod appearance- pod color- seed texture- seed color- flower color

MENDEL’S EXPERIMENT

1. GREW ONLY PLANTS THAT WERE PURE FOR EACH TRAIT.

-he had plants self-pollinate for several generations.

2. CROSS-POLLINATED CONTRASTING TRAITS.-ex: he crossed a yellow pod plant with a

green.3. THE 1ST CROSS WAS LABELED AS THE PARENTAL

GENERATION (P).

4. THE OFFSPRING WERE LABELED AS THE F1 GENERATION

5. MENDEL ALLOWED THE F1 GENERATION TO SELF-POLLINATE & THOSE OFFSPRING WERE THE F2 GENERATION.

MENDEL’S RESULTS

• AFTER CROSSING A PURE GREEN PODDED PLANT (P) WITH A PURE YELLOW (P) ALL OF THE OFFSPRING WERE GREEN.

• AFTER THESE OFFSPRING (F1) WERE CROSSED THE RESULTING OFFSPRING (F2) CAME OUT TO A 3 TO 1 RATIO FOR GREEN PODDED PLANTS.

MENDEL’S LAWS

• LAW OF SEGREGATION - - two alleles for a character will separate when a gamete

is formed• LAW OF INDEPENDENT ASSORTMENT: -The factors for different characteristics are not connected

QUESTION

EXPLAIN WHY MENDEL GOT THE RESULTS HE DID WITH THE PARENTAL

GENERATION?

ANSWER

Because the green color is considered dominant & it covers or masks the

yellow color trait (recessive)

QUESTION

If all of the offspring were green and then they were cross pollinated, why didn’t

these offspring come out all green?

ANSWERBecause the offspring from F1 generation carried a hidden yellow factor that could be

passed on to the offspring of F2 generation.

The Testcross

• A genetic procedure devised by Mendel to determine an individual’s actual genetic composition

• A purple-flowered plant can be homozygous dominant (PP) or heterozygous (Pp)

• One cannot tell by simply looking at the phenotype

• One can tell from the results of a cross between the test plant and a homozygous recessive plant

How Mendel used the testcross to detect heterozygotes.

BRAIN POP: HEREDITY

https://www.brainpop.com/science/cellularlifeandgenetics/heredity/

GENETIC TERMS

• Gene: a sequence of DNA that encodes for a certain trait

• Allele: one of two (or more) alternative forms of a gene (a single letter)

• Dominant Allele: an allele that dictates the expression of a trait (capital letter, ex: A)

• Recessive Allele: an allele whose trait is masked by the presence of a dominant allele (lower case letter, ex: a)

• Genotype: genetic make-up of an organism (letter combination)

• Phenotype: physical appearance of an organism (its outward appearance)

• Homozygous: both alleles in a gene pair code for the same trait (ex: AA or aa)

• Heterozygous: the two alleles in a gene pair that do not code for the same trait (ex: Aa)

TERMS

• Sex Chromosome: the chromosome that determines the sex of an organism (the X and Y chromosome)

• Autosome: any chromosome that is not a sex chromosome

• Punnett Square: a chart which shows all possible gene combinations in a cross of parents

• Monohybrid cross: a cross between two individuals for one trait (ex: Aa x Aa)

• Dihybrid cross: crossing two different characteristics at the same time (AaBb x AaBb)

TERMS

GeneticsFriday, January 9th, 2015

Agenda: Welcome Back!!

Notes: Genotypic vs. Phenotypic Ratios

Activity: Monohybrid Cross Practice

Homework/Class Work:Genetic Practice Problems II Worksheet due Monday 1/12/2015 for 15 Points

Genotypic Ratio VS Phenotypic Ratio

• Genotypic Ratio: the number of times each genotype appears in the offspring. Written from most dominant trait to the recessive.

( # of AA, # of Aa, # of aa)

• Phenotypic Ratio: the number of times each phenotype appears in the offspring. Written from the dominant trait to the recessive.

(# of dominant, # of recessive)

Punnett Squares• A Punnett square is a chart which shows all possible

gene combinations in a cross of parents. • Horizontally across the top of the chart are the

possible gametes of one parent.• Vertically down the side of the chart are the

possible gametes of the other parent.• In the boxes of the chart are the possible genotypes

of the offspring.

T T

t

t

T

T

T

T

t

t

t

t

TT x tt

LET’S TRY ONE!!!!*Brown = dominant*

B= brown eyesb= blue eyes

Bb x bb

B b

b

b

The genotypic ratio is:

The phenotypic ratio is:

0:2:2

2:2

B

bB

bb

b

b

b

C= Straight hairc= curly hair

Monohybrid Cross: two heterozygousindividualsCc x Cc C c

C

c

GENOTYPIC RATIO:

PHENOTYPIC RATIO:

1:2:1

3:1

Homozygous dominant: Heterozygous: Homozygous recessive

CC:Cc:cc

Straight:curlyDominant:Recessive

CC Cc

Cc cc

IN YOUR NOTEBOOK…