genetics gregor mendel and his work. genetics the study of heredity the way in which traits of...
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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)