GeneticsGREGOR MENDEL and

HIS WORK

Genetics• the study of heredity

• the way in which traits of parents are passed on to offspring

Austrian Monk Considered the “Father of

Heredity”

did experiments with peas and proved that certain

characteristics……..

Gregor Mendel

……….• Such as color and height,

are passed from parent to offspring

Differences• all differences in organisms are

not caused by genetics

• some are caused by the environment

• the conditions under which the animals are raised

Dominant and

Recessive Traits

Dominant Traits

Dominant traits are characteristics that people see you have

Symbols• dominant genes

• capital letters

Recessive Traits

Recessive traits are

characteristics that you have which people

cannot see

Symbols

• recessive genes

• lower case letters

When someone has a recessive trait that can be seen, it means that

they inherited one recessive trait from

each parent

What are some dominant and recessive

traits?DOMINANT RECESSIVE

BROWN EYES BLUE EYES

CAN ROLLTONGUE

CANNOT ROLLTONGUE

BROWN HAIR BLONDE/RED

SIX FINGERS! FIVE FINGERS

Phenotypes

THE EXTERNAL APPEARANCE

OF AN ORGANISM

GenotypesTHE

GENETIC MAKEUP

OF AN ORGANISM

MENDEL’S

GENETICS

Mendel studied 7 traits in peas.

*SEED SHAPE*SEED COLOR*POD SHAPE*POD COLOR*FLOWER COLOR*FLOWER LOCATION*STEM SIZE

•HE PLANTED EACH TYPE IN A SEPARATE GARDEN

• GREW THEM UNTIL HE WAS SURE THAT ALL TALL PLANTS PRODUCED TALL PLANTS & ALL ROUND PEA PLANTS PRODUCED ROUND PEAS AND SO ON…

IN OTHER WORDS, HE GREW AND POLLINATED PUREBRED

PLANTS

TALL WITH TALL

ROUND PEAS WITH ROUND PEAS

SHORT WITH SHORT

ETC...

THEN HE TRANSFERRED THE

POLLEN OF THE TALL PLANT TO

THE SHORT PLANT, THE ROUND PEA TO

THE WRINKLED PEA, ETC….

HE FOUND THAT ALL ROUND PEA PLANTS CROSSED WITH

WRINKLED PEA PLANTS PRODUCED ROUND PEAS

PLANTS

WHATEVER HAD CAUSED THE PLANT TO BE WRINKLED HAD DISAPPEARED

HE REPEATED THIS WITH EACH PHENOTYPE

HE FOUND THAT THE RECESSIVE

TRAITS WERE STILL THERE,

JUST HIDDEN

HE CALLED THE TRAITS THATWERE SEEN :

HE CALLED THE TRAITS THATWERE NOT SEEN :

DOMINANT

RECESSIVE

HE CALLED THE OFFSPRING WITH ONE DOMINANT FACTOR AND ONE

RECESSIVE FACTOR: HYBRID

MEIOSIS

Nucleus• contains the genetic material

Chromosomes• carry the genes

• exist in pairs in all cells except sperm and egg cells

Genes• single determiner of a

hereditary trait

Cell Division• two types

• Mitosis

• Meiosis

Mitosis• cell division for growth

• this division never ends

• chromosome pairs are duplicated exactly alike

MitosisSteps of mitosis

• Interphase

• Prophase

• Metaphase

• Anaphase

•Telophase

•Cytokinesis

Dominant gene• in a pair, hides the effect of

another gene

IF YOU RECALL...

Recessive gene• the gene which is hidden by a

dominant gene

Gamete• mature egg or sperm cell

• each gamete has half the original number of chromosomes

Examplesof dominant genes

• tongue rolling

• free ear lobes

• brown hair

Examplesof recessive genes

• color red in Holsteins(cows)

• dwarfism

T t

T t

t t

Meiosis

Mitosis

Mitosis

Steps of Meiosis• Interphase

• Prophase I

• Metaphase I

• Anaphase I

• Telophase I

Steps of Meiosis• Interphase• Prophase II • Metaphase II• Anaphase II• Telophase II• Cytokinesis

Meiosis• cell division of reproductive

cells (sperm and egg)

• each new cell is not exactly like the old one

Meiosis• allows for random

assortment of parental genes

Meiosis• in each new cell

chromosomes are not in pairs

• each new cell contains half of the original number of chromosomes

CHROMOSOMES CONDENSE BUT DNA DOES NOT DUPLICATE

PAIRED CHROMATIDS

LINE UP ACROSS MIDDLE OF CELL

CHROMATIDS SEPARATE AND ARE PULLED TO OPPOSITE ENDS

OF CELL

CHROMOSOMES GATHER

IN NUCLEI AND CELL DIVIDES

FOUR CELLS-EACH HAS NUCLEUS & 23

UNPAIRED CHROMOSOMES

Diploid(2n)

Haploid(n)