FUNDAMENTALS OF GENETICS

Chapter 9 Lab BioChapter 12 Honors Bio

Discussion about Lorenzo’s Oil

Brainstorm:- define genetics- define heredity

Anticipatory Set: How important is it to be able to find your own

answers to questions you may face? Does education and learning end with your

high school or college years? How do you plan to develop the skills to

become a life long learner?

Marfan Syndrome

Do you think he has Marfan Syndrome? Why?

Does Obama have Marfan Syndrome?

Abraham Lincoln had Marfan Syndrome.

Cyctic Fibrosis

Genetics

The study of how characteristics are transmitted from parent to offspring

What is HEREDITY?

The transmission of characteristics from parent to offspring

Vocabulary

Chromosome: structure within nucleus, made of DNA

Gene: unit of heredity found in DNA molecule (words)

Allele: symbols (letter) used to represent genes ex: T=tall, t=short

Dominant: trait/characteristic that are expressed – represented with capital letter

Recessive: trait/characteristic that may not be expressed (always lower case) ex: t=short

Continued Vocabulary

Homozygous/pure: both alleles are alike ex: TT or tt

Heterozygous/hybrid: alleles differ ex: Tt Genotype: genetic make up ex: (pure

homozygous) tall, hybrid (hetero.) tall Phenotype: what you see (physical

appearance) ex: tall, short Cross: symbolic of reproduction ____ X _____ P: parent generation F1: first generation

Where are the genes????

Can you see where the genes are?

NOW can you see where the genes are???

CHROMOSOMES AND GENES

A GENE is the segment of DNA on a chromosome that controls a particular trait.

Chromosomes are in pairs i.e. Genes occur in pairs (each of several

alternative forms of a gene is called an ALLELE

MENDEL’S FACTORS ARE NOW KNOW AS ALLELES!!!!!!

Letters used to represent alleles:

CAPITAL = Dominant alleles Lower case = recessive alleles Example: P = purple color (dom.) p = white color (rec.) When gametes combine in fertilization

offspring receive ONE ALLELE for a given trait from EACH PARENT!

Genetic Crosses

Helps us predict the likely outcome of offspring!!

1. genotype: genetic make-up, consists of alleles Ex: P=purple, p=white Pp = purple PP = purple White = pp

Continue…

2. Phenotype = appearance of an offspring (what you see)Ex: purple flowers, white flowers, hair color

Continue…

3. Homozygous = when both alleles of a pair are alike

Ex: tt, TT, PP, ppHomozygouse recessive = pp

Homozygouse dominant = PP

Continue…

4. Heterozygous = two alleles in a pair are different

Ex: Pp or Tt

Brainstorm/Anticipatory Set

Do you think that we could make as many discoveries in science if we didn’t use animals? Explain…..

Gregor Mendel

!

A little background…

Austrian Monk Studied garden pea plants

(Pisum sativum) 1842 he entered the monastery

in Austria 1851 enetered Univ. of Vienna

to study science and mathematics (statistics)

Mendel’s Pea Plants

Observed 7 characteristics each in 2 contrasting traits: Long short stems Axial terminal (flower position) Green yellow (pod color) Inflated constricted (pod appearance) Smooth wrinkled (seed texture) Yellow green (seed color) Purple white (flower color)

Pea Pods!!!

Some more pea plants…

Flowering Pea Plants!

Mendel’s Methods

He controlled how pea plants were POLLINATED!!! SELF POLLINATION=pollen is transferred from

anthers (male) of a flower to stigma (female) of same flower or flower on the same plant

CROSS POLLINATION=involves flowers of 2 separate plants

Flower!!

How to interrupt self pollination!

1. remove anthers from a flower

2. manually transfer the anther of a flower on one plant to stigma of a flower on another plant

Mendel’s Experiments:Pure Trait

P1 (cross) pure Purple x pure White Law of Dominance F1 ALL came out PURPLE

F1 (cross) Purple x Purple Law of Segregation F2 ¾ PURPLE, ¼ WHITE

Recessive & Dominant Traits

Mendel hypothesized that the trait appearing in the F1 generation was controlled by a DOMINANT FACTOR (allele) because it masked, or dominated, the other factor for a specific characteristic.

RECESSIVE is the trait that did not appear in the F1 generation but reappeared in the F2 generation.

The Law of Segregation

A pair of factors (alleles) is segregated (or separated) during the formation of gametes

Each reproductive cell (gamete) receives only one factor (allele) of each pair.

Crossed two heterozygous purple plants!

Law of Segregation

Test Cross- Unknown Genotype

Is the purple plant homozygous or heterozygous ?

Perform a test cross!

Always! Cross the unknown with a homozygous recessive

Test Cross

Practice!

g

g

G G

G G

g g

g g

P

F1

Key: G=greeng= yellow

Phenotype:100% green

Genotype:100% heterozygous

? x gg

Practice! ?

? x ggP

F1

Key: G=greeng= yellow

Phenotype:50% green50% yellow

Genotype:

INCOMPLETE DOMINANCE AND CO-DOMINANCE

Incomplete Dominance

Neither allele is dominant In some cases, an intermediate

phenotype is shown

Snapdragons

In snapdragons, flower color can be red, pink, or white. The heterozygous condition results in pink flowers

rr RrRR

Incomplete Dominance Cross

Key:R= Redr= White

F1 Phenotype:100% pink

F1 Genotype:100% heterozygous Rr

F1 Cross

Key:R= Redr= White

Phenotype: 1:2:125% Red25% White50% Pink

Genotype: 1:2:125% homozygous RR 25% homozygous rr50% heterozygous Rr

Other ways to represent incomplete dominance

Co-dominance Both alleles are expressed equally Neither allele is more dominant

than the other

Erminette chickens

Roan Cows

Co-Dominance Erminette Chicken

P generation Black chicken X White

chicken

F1 generation = erminette (checkered patterned)

Key:B =BlackB1 = White

B B

B1

B1

B

BB

B B1

B1

B1

B1

Phenotype: 4:0 or 1:0100% erminette

Genotype: 4:0 or 1:0100% heterozygous

Erminette chicken

BB BW

BB

BW

BB BB BB

BB BW

BW

BW BW

Key:B= BlackW= White

Key:BB =BlackBW = White

B1

B1

B2

B2

B1 B1

B1

B1 B2

B2 B2 B2

Key:B1 =BlackB2 = White

Do Now

1. What does recombination mean?

2. Do you know of any traits that seems to be inherited together? Ex: red hair and fair skin……

Anticipatory Set

Does anyone here look “nothing” like their parents?

If not do you know someone who looks nothing like their family members?

Can we explain this genetically?

Answer….

Traits are inherited independently of each other unless they are linked.

Random Assortment

Genetically Unique

Independent Assortment

Independent Assortment is the random assortment of chromosomes during the production of gametes, the result are genetically unique individual gametes.

The Law of Independent Assortment

He also crossed plants with 2 different characteristics Ex: flower color & seed color

FACTORS FOR DIFFERENT CHARACTERISTICS ARE DISTRIBUTED TO GAMETES INDEPENDENTLY.

Ex: Pure tall yellow x pure short green TTYY x ttyy

Law of Independent Assortment

SEX DETERMINATION AND SEX-LINKED INHERITANCE

Sex Determination

Xy =

XX= female

male

Female karyotype

Male karyotype

X and Y chromosomes

Nondisjunction- Jigsaw

Nondisjunction: failure of chromosomes to separate during meiosis 1 or 2

Results in an extra chromosome or a missing chromosome

http://glencoe.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::550::400::/sites/dl/free/0078757134/383925/Chapter11_NGS_VisualizingNondisjunction_10_10_06.swf::Visualizing%20Nondisjunction

XO- Turner Syndrome XXX- Trisomy X XXY- Klinefelter Syndrome XYY- Jacob Syndrome

Very often, symptoms are slight due to X-inactivation and the small amount of genes found on the Y chromosome

SEX CHROMOSOMES CONTAIN GENES THAT CODE FOR TRAITS

=SEX LINKED TRAITS

Both Males and Females Inherit X Chromosomes: Males XY; Females

XX

X-LINKED GENES: Genes carried on the X chromosomeHemophilia

Color blindnessBaldness Muscular Dystrophy

Mother Without hemophilia = X X

Without hemophilia = X X

With hemophilia = X X Father

Without hemophilia = X y

With hemophilia = X y

H H

H h

h h

CARRIER

H

h

Key!

MULTIPLE ALLELES- BLOOD TYPING

How common is your blood type?

46.1%

38.8%

11.1%

3.9%

Genetics of Blood Types

Human blood type is determined by co-dominant alleles

Antigens-proteins-exist on the surface of all of your red blood cells.

Blood types

For simplicity

IA A

IB B

i O

Antibodies

Found in the plasma Specific to a single kind of

antigen Attack and kill that specific kind

of antigen

What are blood types?

http://learn.genetics.utah.edu/units/basics/blood/types.cfm

• There are 3 alleles for blood type: A, B, O

• Since we have 2 genes: 6 possible combinations

Blood Types

AA or AO = Type ABB or BO = Type B

OO = Type OAB = Type AB

RBC= Red Blood Cell = antibody

Antibody B- protects the body by attacking foreign B antigen blood

Scenario B

Scenario AB

Scenario O

Blood Transfusions

Blood transfusions – used to replace blood lost during surgery or a serious injury or if the body can't make blood properly because of an illness.

Who can give you blood?

TYPE O -Universal Donors

can give blood to any blood type

• No antigens present on RBC

TYPE AB- Universal Recipients

can receive any blood type

• No antibodies present in plasma

Universal Donor

Universal Recipient

Rh Factors Rhesus monkeys –contain certain

similarities with humans A blood protein was discovered and present

in the blood of some people The presence of the protein, or lack of it, is

referred to as the Rh (for Rhesus) factor.

Rh positive (Rh+) - contain the protein Rh negative (Rh-)- NOT contain the protein A+ A-

B+ B-AB+ AB-O+ O-

http://www.fi.edu/biosci/blood/rh.html

Rh factor Possible genotypes

Rh+ Rh+/Rh+

Rh+/Rh-

Rh- Rh-/Rh-

PEDIGREE ANALYSIS

Have you ever seen a family tree… do you have one??

Graphic representation of family inheritance.

Pedigree of Queen Victoria

What is a pedigree? Shows a pattern of inheritance in a family

for a specific trait (phenotype) Genotypes can usually be determined

Why would we want to use a pedigree in

genetics? Track the occurrence of diseases such as:

Huntington’s – simple dominant – lethal allele – causes breakdown of the brain

Cystic fibrosis – 1/2500 – mucus accumulates (white North Amer.)

Tay-Sachs disease – lipids accumulate in CNS (Jewish)

Phenylketonuria – missing enzyme causes problems in CNS (Nordic/Swedish)

The Symbols used:

Sample pedigree:• generations are numbered with Roman Numerals• oldest offspring are on the left

Inheritance patterns: Autosomal dominant:

–Examples: Polydactyly

–Huntington’s disease

The disease is passed from the father (II-3) to the son (III-5), this never happens with X-linked traits.

The disease occurs in three consecutive generations, this is rare with recessive traits.

Males and females are affected, with roughly the same probability.

Inheritance patterns: Autosomal recessive

– Cystic fibrosis– Tay-Sach’s disease

Males and females are equally likely to be affected.

The trait is characteristically found in siblings, not parents of affected or the offspring of affected.

Parents of affected children may be related. The rarer the trait in the general population, the more likely a consanguineous mating is involved.

Inheritance patterns: Sex-linked recessive conditions

– Examples:

– Color-blindness

– Duchenne Muscular Dystrophy

The disease is never passed from father to son.

Males are much more likely to be affected than females.

• All affected males in a family are related through their mothers.

Trait or disease is typically passed from an affected grandfather, through his carrier daughters, to half of his grandsons.

Method 1: Process of Elimination

• X-linked recessive

• Autosomal

dominant

• Autosomal

recessive

Method 2: Recognizing Patterns

• X-linked recessive

• Autosomal

dominant

• Autosomal

recessive

Practice!

• X-linked recessive

• Autosomal

dominant

• Autosomal

recessive

Mendel’s Rules Apply to:

Law of Dominance Law of Segregation Test Cross MENDEL’S RULES DO NOT APPLY TO: Incomplete dominance Multiple alleles Codominmanmce Polygenic inheritance Pleiotyropy Environmental influence

What you must know!

Law of dominance Law of segregation Test cross Incomplete dominance Codominance Independent assortment Sex determination Sex linkage Multiple alleles