Download Introduction to Genetics

Genetics
Why do organisms look or behave in certain ways?
Why do kids look similar to their parents?
https://www.youtube.com/watch?v=B_PQ8qYtUL0
Traits
• Traits are a feature you inherit.
• Traits are passed from parents to offspring.
• Sexually reproduced organisms are a unique blend of
both parent’s traits
• Traits can be physical or behavioral.
• Physical traits in animals can include features such
as wings, claws, fur, which may provide advantages
for that organism, we call these adaptations.
• Or the physical traits may just influence the
appearance of an organism such as eye color, hair
color, or right/left handedness.
• Behavioral traits may include actions such as nestbuilding, swimming, or migrating.
• Human behavioral traits can include being diurnal,
flinching, and the moro-reflex (falling reflex)
Traits can be used for security to
identify each unique person.
So how does each trait get passed
from parents to form in an offspring?
• Your DNA provides the instructions for your
types of traits.
• Your body is made of trillions of cells, each one
with a nucleus.
• Inside each nucleus are 46 chromosomes.
You got 23 from mom, 23 from dad
• Chromosomes are made of many genes
• A gene is a long section of DNA (deoxyribonucleic acid)
https://www.youtube.com/watch?v=5MQdXjRPHmQ (4:56)
DNA
http://abcnews.go.com/blogs/business/2013/04/letter-on-dna-structure-sells-for-record-5-3-million/
Put these in order, largest to smallest
Answer:
Cell
Nucleus
Chromosome
Gene
DNA
Label your picture
What is DNA and how does it work?
https://www.youtube.com/watch?v=zwibgNGe4aY (5:24)
• Ribosomes “read” the DNA and make proteins
• Proteins make up all the cells and structures of
your body (fingernails, skin, muscles, etc.)
• Proteins also make enzymes which help
chemical reactions, like digestion, occur in your
body.
https://www.youtube.com/watch?v=tI69AVRW0DU (9:48)
what are enzymes
• Every inherited trait is controlled by one or more
proteins
DNA and our genes are a code for
making proteins which make our
traits
Traits –
including hair
color and
poor eyesight,
are passed
from
generation to
generation
Traits are passed from parents to
offspring in different combinations
each time.
Making you one of a kind!
A Survey of Human Traits
Trait
• A feature you inherit. (eye color, freckles,
body structure, etc.)
Allele
• Alternate form of a gene for a trait
– Blue or Brown are alleles for eye color
– Allele may be dominant or recessive (B or b)
Dominant
• A trait that covers over another form of that
trait.
– Represented with a capital letter (B)
Recessive
• A trait that gets covered up by the
dominant allele and it seems to disappear.
– Represented with a lower case letter (b)
Phenotype
• The outward, physical appearance of an
organism as a result of its genotype.
(brown hair, left handed, freckles)
• What is her phenotype?
– Brown eyes, brown hair,
curly hair, no freckles,
medium skin tone
Genotype
• The genetic make-up of an organism
– Represented by two alleles (one from mom,
one from dad)
– BB, Bb, bb (homozygous or heterozygous)
Survey yourself
• Look at each trait and determine your
phenotype (outward appearance)
• Next, determine your genotype (what
letters/alleles you have for the trait.)
• You may have dominant, recessive, or
hybrid alleles
• We will work through this together…
Handedness
• Phenotype:
– Right or Left
• Genotype:
– Right = RR or Rr
– Left = rr
Hitchhiker’s thumb
• Phenotype:
– Present (top) or Absent
(bottom)
• Genotype:
– Present (HH or Hh)
– Absent (hh)
Ear lobes
• Phenotype:
– Unattached (top) or
attached (bottom)
• Genotype:
– Unattached (LL or Ll)
– Attached (ll)
Tongue Rolling
• Phenotype:
– Roller or non-roller
• Genotype:
– Roller (RR or Rr)
– Non-Roller (rr)
Widow’s Peak
• Phenotype:
– Present (see pictures) or
absent
• Genotype:
– Present (WW or Ww)
– Absent (ww)
Dimples
• Phenotype:
– Present (see
pictures) or absent
• Genotype:
– Present (DD or Dd)
– Absent (dd)
Cleft Chin
• Phenotype:
– Present (see
pictures) or absent
• Genotype:
– Present (CC or Cc)
– Absent (cc)
Interlocking fingers
• Phenotype:
– Left thumb on top or
right thumb on top
• Genotype:
– Left on top (TT or Tt)
– Right on top (tt)
PTC Taster
• Phenotype:
– Taster or non-taster
• Genotype:
– Taster (PP or Pp)
– Non-taster (pp)
Tonight
• Survey your family members. See who
has what phenotypes.
• Can you figure out where some of your
genes came from?