Transcript genes - Sophia

Living Organisms
Some basic characteristics of life:
Need
H2O
GAS
EXCHANGE
Need
NUTRIENTS
Made of
CELLS
REPRODUCE
Living Organisms
Some basic characteristics of life:
All living things
need
H2O
Living Organisms
Some basic characteristics of life:
Living things Need
NUTRIENTS
Living Organisms
Some basic characteristics of life:
Living things have
a system for
GAS
EXCHANGE
Living Organisms
Some basic characteristics of life:
Made of
CELLS
Living Organisms
Some basic characteristics of life:
All living things
REPRODUCE
ASEXUALLY
SEXUALLY
to create new individuals
that are clones
to create new individuals
with a combination of traits
ASEXUAL
REPRODUCTION
• Only one parent reproduces.
• The same genetic material (DNA) is passed
directly from parent to offspring.
• All offspring are CLONES of the parent
and have the exact same traits.
Types of Asexual Reproduction
• Fission
Cell division by a parent cell splitting into two parts,
each growing into a new exact copy of the parent cell.
• Budding
To develop as a growth on a parent, then break off and
mature into a new exact copy of the parent.
• Fragmentation and Regeneration
Offspring can grow from a fragment (piece) of the
parent, or the parent can re-generate the missing piece.
FISSION
FISSION
BUDDING
Planarians
are flat worms
that can be
rapidly regenerate.
Fragmentation
They can be cut
across or along
their body.
Regeneration
SEXUAL
REPRODUCTION
• Two parents (of opposite sex) reproduce.
• Two sex cells (one from each parent)
combine during fertilization.
• Parents combine genetic material (DNA) to
form offspring that has a COMBINATION
of parent’s traits.
Sperm
23 x
Egg
23 X
zygote
46 X
Female cell
divides to
produce
eggs
Contains half
of the
mother’s DNA
Male cell
divides to
produce
sperm
Contains half
of the
father’s DNA
Mothers half
+ fathers half
= Full set of DNA
Genes and Chromosomes
GENES and CHROMOSOMES
• Inside the cell nucleus are chromosomes.
• Chromosomes are bundles of tightly coiled
strands of long molecules called DNA.
• A segment of DNA codes for a trait.
• These segments are called GENES.
A gene codes
for a specific
type of trait.
Each trait is
determined by
a pair of
GENES.
A chromosome is a bundle of DNA.
Segments of DNA are genes.
Gregor Mendel
-Austrian Monk
-Gardener/Scientist
-Worked with peas
-Noticed patterns of
traits in generations
-Developed the main
idea of heredity
Gregor Mendel
determined that…
• Each trait is determined by a pair of genes
– one from each parent.
• Both parents contribute equally to your genes.
• A gene is either dominant or recessive.
• Three possible gene pairs for any trait:
2 dominant genes
2 recessive genes
1 dom and 1 rec gene
Dominant Genes
• Dominant genes are ‘stronger’ than recessive
genes, and can cover them up.
• If at least one gene in the gene pair is
dominant, then the individual will ‘express’ the
dominant form of the trait.
• Represented with a CAPITAL letter… Usually
the first letter of the trait.
• Ex: Black fur is dominant, so
B = a dominant gene.
Recessive Genes
• Recessive genes are weaker, and cannot cover
up dominant genes.
• ONLY if both genes in the gene pair are
recessive, then the individual will ‘express’ the
recessive form of the trait.
• Represented with a lower case letter..
Usually the first letter of the trait.
• Ex: Black fur is dominant, white fur is
recessive, so b = a recessive gene.
Genotypes and Phenotypes
Possible gene
combinations
Genotype
AA
2 dominant genes
Purebred dominant
1 dominant gene
and
1 recessive gene
Aa
Hybrid
aa
2 recessive genes
Purebred recessive
Phenotype
Dominant trait
expressed
Dominant trait
expressed
Recessive trait
expressed
Gregor Mendel
studied many
traits of pea
plants, like seed
color and shape,
and the color of
the petals.
Traits in Humans
Dominant
•
•
•
•
•
•
•
•
•
Brown eyes
farsightedness
normal vision
normal vision
normal vision
Dimples
unattached earlobes
Freckles
broad lips
Recessive
•
•
•
•
•
•
•
•
•
Gray, blue, green, hazel
normal vision
Nearsightedness
night blindness
color blindness*
no dimples
attached earlobes
no freckles
thin lips
Practice Questions
DIMPLES ARE DOMINANT
OVER DIMPLE-LESSNESS.
What is the genotype of someone who has
no dimples?
dd
What is the phenotype of someone who has
a genotype of Dd?
They have dimples.
Practice Questions
CURLY HAIR IS DOMINANT OVER STRAIT.
What is the genotype of someone who has
curly hair?
CC or Cc
What is the phenotype of someone who has a
genotype of cc?
They have straight hair.
Practice Questions
Which of the gene pairs are:
Purebred dominant?
Aa
BB
Cc
dd
Hybrid?
Purebred recessive?
ee
FF
Gg
hh