Transcript Week 6 Notes Probability and Heredity & The Cell and

Week 6 Notes
Probability and
Heredity & The Cell and
Inheritance
Pages 84 – 89 and Pages 92 – 96
I. Probability
A. PRINCIPLES OF PROBABLILITY
a. __PROBABILITY__ is a __NUMBER__ that describes
how __LIKELY__ it is that an __EVENT__ will occur.
1. Mathematics of Probability
a. The laws of probability __PREDICT__ what is likely to
occur, not necessarily what will occur.
2. Independence of Events
a. __RESULTS__ of one event __DO NOT__ affect the
results of the next event
b. In a coin toss, the __RESULTS__ of any amount of tosses
__DO NOT__ affect the __RESULTS__ of the next toss.
B. PROBABILITY AND GENETICS
1. Punnett Squares
a. A __PUNNETT SQUARE__ is a chart that shows all the
__POSSIBLE__ combinations of __ALLELES__ that can
result from a __GENETIC CROSS__
b. The __BOXES__ in the __PUNNETT SQUARE__
represent the possible __COMBINATIONS__ of alleles
that the __OFFSPRING__ can __INHEREIT__
2. Using a Punnett Square
a. In a __GENETIC__ cross, the __ALLELE__ that each
parent will __PASS__ on to its offspring is based on
__PROBABILITY__
b. When __MENDEL__ crossed __HYBRID__ plants with
round seeds, he discovered that about __3__ out of the 4
plants had round seeds.
c. __DOMINANT__ alleles __MASKS__ the
__RECESSIVE__ allele.
3. Predicting Probabilities
a. You can use a __PUNNETT SQUARE__ to predict
__PROBABILITIES__
C. PHENOTYPES and
GENOTYPES
a. __PHENOTYPE__ is an organisms __PHYSICAL__ traits,
or __VISIBLE__ traits
b. Examples: __EAR LOBES__, __HAIR COLOR__,
__TONGUE ROLLING__
c. __GENOTYPES__ is an organisms __GENETIC__
makeup, or __ALLELEL COMBINATION__
d. Examples: __R R__, __r r__, __R r__
C. PHENOTYPES and
GENOTYPES Cont.
e. An organism that has 2 __IDENTICAL__ alleles for a
__TRAIT__ is said to be __HOMOZYGOUS__ for that trait.
f. Example: __R R__ or __r r__
g. An organism that has 2 __DIFFERNET__ alleles a trait is called
__HETEROZYGOUS__ for that trait
h. Example: __R r__
i. __HYBRID__ is a word that __MENDEL__ used for
__HETEROZYGOUS__
D. CODOMINANCE
a. For __CODOMINANCE__ the alleles are __NEITHER__
dominant nor recessive. __BOTH__ alleles are expressed
in the __OFFSPRING__
II. The Cell and Inheritance
A. CHROMOSOMES and INHERITANCE
a. Sex cells have __HALF__ the number of
__CHROMOSOMES__ than other __CELLS__
1. Chromosome Pairs
a. Most cells in the body have __46__ chromosomes; in
__SEX__ cells there is __23__
b. For a normal cell __23__ come from your __MOTHER__
and __23__ come from your __FATHER__
2. Genes on Chromosomes
a. __GENES__ are carried from __PARENTS__ to their
__OFFSPRING__ on __CHROMOSOMES__
B. MEIOSIS
a. __MEIOSIS__ is the process by which the __NUMBER__
of __CHROMOSOMES__ is reduced by __HALF__ to
form sex cells – __SPERM__ and __EGGS__
1. What Happens During Meiosis
a. During __MEIOSIS__ the __CHROMOSOME pairs
__SEPARATE__ and are distributed to __2__ different
__CELLS__
b. __NORMAL__ cells have __4__ chromosomes, a __SEX__ cell
has __2__ chromosomes
c. __SEX__cells combine to form an __ORGANISM__ each sex
__CELL__ contributes __HALF__ the normal number of
__CHROMOSOMES__.
d. The __OFFSPRING__ gets the __NORMAL__ number of
chromosomes – __HALF__ from each __PARENT__
2. Meiosis and Punnett Squares
a. A __PUNNETT SQUARE__ is actually a way to show the
__EVENTS__ that occur at __MEIOSIS__
b. When the __CHROMOSOMES__ pairs separate and go
into __2__ different sex __CELLS__, so do the
__ALLELES__ carried on each __CHROMOSOME__.
C. A LINEUP OF GENES
a. __HUMAN__ body cells contain __23__ chromosomes
pairs, or __46__ chromosomes.
b. Chromosomes are made up of many __GENES__ joined
together like beads on a string.
c. Human body __CELLS__ contain between __20,000__
and __25,000__ genes. Each __GENE__ control a
__TRAIT__