Living Organisms Some basic characteristics of life: Need NUTRIENTS Need H 2 O GASEXCHANGE Made of...
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Transcript of Living Organisms Some basic characteristics of life: Need NUTRIENTS Need H 2 O GASEXCHANGE Made of...
Living OrganismsSome basic characteristics of life:
Need
NUTRIENTS
Need H2O
GAS GAS EXCHANGEEXCHANGE
Made of
CELLS REPRODUCE
Living OrganismsSome basic characteristics of life:
All living things need H2O
Living OrganismsSome basic characteristics of life:
Living things Need
NUTRIENTS
Living OrganismsSome basic characteristics of life:
Living things have Living things have a system fora system for
GAS GAS EXCHANGEEXCHANGE
Living OrganismsSome basic characteristics of life:
Made of
CELLS
Living OrganismsSome basic characteristics of life:
All living things REPRODUCE
ASEXUALLYASEXUALLY
to create new individuals that are clonesclones
SEXUALLYSEXUALLY
to create new individualswith a combination of traitscombination of traits
• 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.
ASEXUALASEXUAL REPRODUCTION
Types of Asexual Types of Asexual ReproductionReproduction
• FissionCell 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.
They can be cut across or along
their body.
Fragmentation
Regeneration
• 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.
SEXUALSEXUAL REPRODUCTION
Egg
23 X
Sperm23 x
zygote46 X
Contains half of the
mother’s DNA
Contains half of the
father’s DNA
Mothers half + fathers half
= Full set of DNA
Female cell divides to produce
eggs
Male cell divides to produce
sperm
Genes and Chromosomes
GENES and GENES and CHROMOSOMESCHROMOSOMES
• 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 isdetermined by
a pair ofGENES.
A chromosome is a bundle of DNA.Segments of DNA are genes.
Gregor MendelGregor Mendel
-Austrian Monk-Gardener/Scientist-Worked with peas-Noticed patterns of traits in generations-Developed the main idea of heredity
Gregor Mendeldetermined 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 genes2 recessive genes1 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 PhenotypesPossible gene combinations
Genotype Phenotype
2 dominant genes
AAPurebred dominant
Dominant trait expressed
1 dominant gene and 1 recessive gene
AaHybrid
Dominant trait expressed
2 recessive genes
aaPurebred recessive
Recessive trait expressed
Gregor MendelGregor Mendel studied many traits of pea plants, like seed color and shape, and the color of the petals.
Traits in Humans Dominant
Recessive • Brown eyes• farsightedness• normal vision• normal vision• normal vision• Dimples• unattached
earlobes• Freckles• broad lips
• 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?
What is the phenotype of someone who has a genotype of Dd?
dd
They have dimples.
Practice Questions
CURLY HAIR IS DOMINANT OVER STRAIT.
What is the genotype of someone who has curly hair?
What is the phenotype of someone who has a genotype of cc?
CC or Cc
They have straight hair.
Practice Questions
Which of the gene pairs are:
Purebred dominant?
Hybrid?
Purebred recessive?
Aa BB
Cc dd
ee FF
Gg hh