Unit 3 Study Guide

Inheritance of Genes

-Sexually reproductive organisms inherit one copy of each chromosome from each parent
--Humans, 23 from mom, 23 from dad
-Each parent may possess a different allele
-As a result, offspring resemble parents more than others in the population

...pg 1

Gregor Mendel (father of genetics)

-Monk from Czech Republic
-Questioned inheritance
-Studied pea plants
-Focused on easily categorized traits
-Practiced true breeding -- producing offspring with the same trait as the parent
-Mendel studied classical genetics

...pg 2

Allele

Variation of a gene

...pg 4

Dominant

A trait that gets expressed in the heterozygote

...pg 4

Recessive

the trait that does not get expressed in a heterozygote

...pg 4

Heterozygote

possessing two different alleles

...pg 5

Homozygote

Possessing two identical alleles

...pg 5

Phenotype

the outward appearance of an individual (expressed trait)
-flashy coloration, height, presence of antlers
-functional enzymes for blood clotting, lactose digestion

....pg 5

Genotype

The organisms genetic composition (allele combination)
-Heterozygous, homozygous dominant, homozygous recessive
-genotype cannot always be determined with the naked eye

...pg 5

Carrier

a heterozygote that carries a recessive allele that does not get expressed

...pg 5

Law of segregation

-an individual possesses 2 alleles
-these alleles separate during meiosis
-after meiosis, each egg or sperm will only have one allele (instead of 2 in somatic cells)
-during fertilization, a sperm and egg will fuse to create a new individual possessing 2 alleles

...pg 6

Punnett Squares

-predict the possible outcomes of a cross between two individuals
-ex: M = pigmented, m = albino
-How many alleles would on giraffe have for this gene (fur color)
-The recessive trait is always denoted in lower case
-Cross MM x mm using Punnett Square

...pg 7

Pedigrees

-a type of family tree that help couples figure out inheritance
-information gathered from relative
-each row is a generation
-squares are male, circles are females

...pg 8

Beyond Classical Genetics

Mendel studied classical genetics, his pea plants were straightforward

...pg 10

Complex Genetics

when there is more than a single dominant and recessive allele

...pg 10

Incomplete Dominance

-mixture of expression
-heterozygous express an intermediate (mixed) phenotype
-both alleles involved are dominant

...pg 10

Snapdragons

-can be red or white, where C^r = red, C^w = white
-C for color, R for red, W for white
-C^rC^r = red, C^wC^w = white, C^rC^w = pink
-Both alleles are dominant, no recessives

...pg 10

Codominance

-Heterozygous express both phenotypes
-chicken feathers can be black or white
--a heterozygote will have both black or white feathers.
--snapdragons with red and white alleles will have both red ad white spores, not pink like incomplete dominance
Human blood type is an example of codominance

...pg 11

Human blood type

-Codominance genetics, multiple alleles
-three alleles are involved:
--I^A = A protein (dominant)
--I^B = B protein (dominant)
--i = no protein recessive

Six possible genotypes:
--I^AI^A, I^BI^B, I^AI^B, ii, I^A, IBi
How many pheotypes?
4 phenotypes

...pg 11

Sex-linked inheritance

-Genes found on autosomes are not gender biased
-Genes found on the X chromosome has a bias toward gender
-Males have only 1X
-Females have 2Xs

...pg 13

An individual carries two different alleles for a gene, and therefore is _______ for the trait.

Heterozygous

...pg 15

Which blood type can be donated to an other blood type?

Blood Type O

...pg 16

Before Darwin

-Believed Earth was about 6,000 years old
-All living things were all at once
-Darwin forever changed our perspective on human origin and other species

...pg 16

Charles Darwin

-Born 1809, England
-Studied medicine at 16
-Captain of SMS beagle, 5 year voyage
-Starting observing different creatures around him
-Inspired in the Galapagos Islands, studying finches and other organisms

...pg 17

Darwin's finches

-collected finches
-noticed they were different like we are to each other, but realized finches were different species
--Body, beak size, feather color
--Species -- the ability to breed with another
-though finches were different species, they all resembled a species found on the mainland

...pg 18

Theory of Evolution

-Darwin thought perhaps the best individuals would "win" during periods of struggle
-published "The origin of Species"
-an instant hit
-Evolution and natural selection changed the world in scientific thinking

...pg 19

Evolution

-evolution --a genetic change (allele frequency) in a population, does not always result in a new species
-Individuals do not evolve
-The smallest unit that can evolve is a population
-evolution and natural selection are not the same but natural selection is one form of evolution

...pg 20

Mutation

-a change in the base pair of DNA
-if mutation occurs in sex cells (sperm or egg), this trait can be passed down to offspring
-if mutation occurs in somatic cells (all other cell types), cannot be passed down
-can be random
-can be beneficial or detrimental
-ultimate source of genetic variation
-can create a gene that has never existed
-can increase fitness and survival, leading to natural selection
-most have no impact or negative on survival
-are rare
-generally try to protect against mutations

...pg 21-22

Genetic Drift

-Random change in allele frequencies in a population
-Not related to reproductive success
-greater impact on small populations
-can result in the complete loss of an allele known as fixation

...pg 23

Founder effect

-a small number of people moving into a new population, introducing new alleles that

...pg 24

Bottleneck

-a rapid change in an environment leading to massive death. The survivors may not have all the original alleles

...pg 24

Gene flow

-or migration, the movement of some individuals from one population to another
-People are always traveling
-Exotic pets can bring in alleles that will change native animals

...pg 25

Natural selection

-A change in allele frequencies that occurs when individuals with greater reproductive success will increase in population
-takes a lot of time

...pg 26

Reproductive success

-natural selection occurs when certain alleles increase reproductive success

...pg 26

Sexual selection

-a type of natural selection that occurs through greater mating success

...pg 26

Natural selection summary

1. Variation for a trait
-different versions (alleles) of a trait are present
2. Heritability
-alleles may be passed from parent to offspring
3. Reproductive success
-alleles most fit to reproduction in their environment leave more offspring

...pg 26

Survival of the fittest

-has nothing to do with superiority
-has everything to do with reproductive success in a particular environment
-not coined by darwin, but a different scientist
-fitness measures of relative amount of reproduction of an individual
-fitness depends on the environment

...pg 27

Nature against perfection

-Nature is not perfect for a good reason
-Natural selection is too slow to adapt environments that change quickly
-a bad allele may eventually be the good allele, a selection of alleles must be present at all times
-different alleles with equal fitness are all retained
-nature support variety and diversity

...pg 28

Evidence supporting evolution

1. Fossil Record
2. Biogeography
3. Morphology
4. Molecular biology
5. Laboratory research

...pg 29

Fossil record

remains or impressions of ancient organisms
-most remains are decomposed
-extinction events allow for fossils to be preserved
--only 5 mass extinction events
--many organisms have left no fossils, there are many gaps in the fossil record
-Allows us to look at transitional features
-lobed-finned fish evolved into amphibians in Canada

...pg 29

Biogeography

-Study of the distribution patterns of living things around the world
-Habitats closer together have similar organisms, those that are farther are very different
Austrailia -- dominated by marsupials

...pg 31

Morphology

-vertebrate embryos
--gills
--tail
-gills disappear before birth except in fish
-humans don't have tails after birth
-Why do human embryos have these structures if we don't need them? Ancestors

...pg 33

Homologous Structures

-Shared by common ancestors
-bone patterns in vertebrate animals are the same, but are modified

...pg 34

Vestigial structures

-structures with no function
-evidence of evolutionary leftovers
-molars in vampire bats, whales with pelvic bones, human appendix

...pg 34

Molecular biology

-looking at similarities in DNA, RNA, Proteins
-the sequence of DNA is similar to organisms that are closely related

...pg 34

Hemoglobin gene

found in red cells
-humans = 146 acids long
-Rhesus monkey = 138/146 aa are identical 8 changed (mutated)
Dogs = 114/146 identical
birds = 101/146 identical
lampreys = 21/146 identical

...pg 34-35

Laboratory Research

-experiments in the lab can observe and measure evolution as it happens.
-ex: Antibiotics resistance in bacteria

...pg 35

The ultimate source of genetic variation in any population is _____

Mutation

...pg 37

An individual in a population who contributes many new individuals to the population has high ______

fitness

...pg 37

Early Earth

-life is the ability to replicate
-Earth formed 4.5 billion years ago
-First life appeared 3.4 billion years ago as bacteria
-First life did not use oxygen, but grew slowly

...pg 38

Small molecules

-there was no oxygen in the air
-carbons and hydrogens readily bond with each other creating huge variety
-Stanly Miller demonstrated that amino acids could be created in a primordial sea

...pg 38

Life began in 3 phases

Formation of Small molecules
Formation of self-replicating molecules
Development of a membrane

...pg 39

Self-replicating Molecules

-RNA is able to make copies of itself
-originally RNA only carried information for replication
-potentially RNA are the first forms of life
-DNA is double stranded, which my have taken over as the preferred method of preserving information

...pg 40

The membrane develops

-Information on how to build a membrane may have been incorporated in self-replicating molecules
-This makes metabolism possible

...pg 40

Species

-population of organisms that interbreed, or could possibly interbreed under natural conditions, and cannot interbreed with other such groups

...pg 41

Species barriers

Pre-zygote barriers - Individuals are physically unable to mate with each other.
Post-zygote barriers - Matings produce hybrid individuals that do not survive long after fertilization.

...pg 41

Naming species

-we use the linnaeus system
-Every species is given a name that consists of two parts
-Hierarchical system with subgroupings

...pg 43
...pg 43

Speciation

-One species splits into two distinct species
-two phases must occur
--Geographic isolation - physical barrier
--Genetic divergence --New alleles

...pg 44

Allopatric speciation

-occurs as a result of a physical barrier that separates a population and prevents them from reproducing with each other
-two populations will acquire mutations that help them adapt to their own environment
-genetic changes will make the two populations so different, they become their own species

...pg 44

Two types of evolution

-Microevolution
-Macroevolution

...pg 46

Microevolution

-changes in allele frequencies over short periods of time, does not result in speciation

...pg 46

Macroevolution

-microevolution changes over a long period of time that can result in speciation

...pg 46

Domains of life

-prokaryotes
-Archaea bacteria
-Eukaryotes
--Eukaryotes are further broken down into 4 kingdoms
--protists, plants, fungi, animals

...pg 47

First tree of life

-self replicating RNA
-self replicating RNA metabolizing cells
-bacteria
-Eukarya and archaea ancestors split form bacteria
-Fusion of bacterium and archaeon-like prokaryote rise to eukaryotes

...pg 47

Bacteria

-single celled organisms
-no nucleus or organelles
-circular DNA
-reproduce quickly therefore can multiply fast

...pg 48

Bacteria Domain

-They are in your mouth, causes morning breath
-Some are aerobic, others anaerobic

...pg 48

good and bad bacteria

Bad - pathogenic or disease causing
Good - beneficial bacteria

...pg 49

Archaea Domain

-many species live in extreme environments
-dominant in the deep seas
-look similar to bacteria
-however, they also have enzymes and membranes similar to

...pg 49

Eukarya Domain

-unlike prokaryotes, eukaryotes have a nucleus
-4 kingdoms
--protists
--plants
--fungi
--animals

...pg 50

Virus

-viruses are not included in the tree of life
-not considered living
-can only replicate with a host with metabolic processes
-virus lacks their own metabolic activity

...pg 50

LUCA

Last universal common ancestor

...pg 50

Asteroid mass extinction

-Asteroid crash in mexico
-left a cloud of dust and debris that blocked starlight
-the debris held greenhouse gasses that led to climate change
-wiped out 75% of earth's species
-killed most dinosaurs, allowed mammals to thrive
-remaining dinosaurs evolved into birds

...pg 53

the Great dying

-wiped out 95% of marine life, 75% terrestrial
-mass build up of carbon dioxide

...pg 54

Jaws and fins

-earliest vertebrates were fish-like
-initially jawless
-evolution of jaws and fins lead to an explosion of new vertebrates

...pg 54

The movement onto land

-plants which evolved from green algae, made a gradual transition to land in tandem with their symbiotic partners, the fungi.
-came from lobe-finned fishes
-four sturdy fins helped move their body onto land
-requires four major adaptations:
--lungs
--backbones
--four legs
-- eggs that won't dry out

...pg 55

Adaptations of plants to the land

-major transitions in plant life came with the development of a water-retaining covering (the cuticle), embryos that matured inside parent plants, and a "vascular" or fluid-transport system
-later plants went on to develop seeds, which can be thought of as packages containing an embryo and food for it, encased in a tough outer covering

...pg 55

The first to take flight

-were arthropods, a centipede-like creature, laid down the oldest terrestrial animal tracks we know of.
-insects, a variety of arthropod, soon followed in great abundance
-the arthropods were the only land animals for millions of years thereafter.

...pg 55

Amphibians

-"living a double life"
-first stage: water breathing juvenile (tadpole)
-second stage: air breathing adult (frog)
-adults lay eggs in water
-breathe through their skin

...pg 56

Reptiles

-evolved from amphibians
-Have amniotic eggs
--hard shelled eggs
-skin covered in scales
-ectothermic body temperature controlled by the environment

...pg 57

Birds

-Snakes and lizards --> dinosaurs and birds
-feathers and wings
-Endotherms -- body heat is constant and is controlled from cellular respiration
-dinosaurs have similaries to birds

...pg 59

Mammals

-after the amniotic egg, one group became reptiles, the other became mammals
-originally small and nocturnal
-insect eaters
-endothermic -- generate their own body heat
-hair -- insulation
-mammary glands -- produce milk

...pg 59

humans

-Ancestors were lemurs
--tree living
--forward eyes with binocular vision
--rotation of arms
--opposable thumbs, fingers, and toes

...pg 61

Ecology

-study of the interactions between organisms and their environments

...pg 69

Several levels of ecological interactions

-individuals -- studies of individual behaviors
-populations -- a group of a single species
-communities -- all living things within a region
-ecosystems -- includes living and nonliving things within a region

...pg 61

Populations

-Ecologists count the number of individuals
-Various techniques are used to estimate the size of populations whose members can't be counted directly.

...pg 70

Exponential Growth

-occurs when each individual produces more than the single offspring necessary to replace itself

...pg 70

Population Growth

-Population -- a group of organisms of the same species living in a particular geographical region
-growth rate -- the change in the number of individuals in the population in some unit of time

Growth rate = birth rate - death rate

...pg 70

Factors that limit overcrowding of one species:

-reduced food supplies
-reduced space for habitats
-increase in parasites and disease, spread easier due to overcrowding
-increase predation risk

...pg 71

Logistic Growth

-population that initially grow, but whose growth later levels out, have experienced logistic growth, sometimes referred to as the s-shaped growth curve.

...pg 72

Carrying capacity

- the ceiling on the growth, the maximum number of individuals an environment can sustain

...pg 72

Environmental resistance

defined as all the forces of the environment that act to limit population growth

...pg 72

Variations in investment of energy in reproduction Vs. Care

-Fish -- highest investment in reproduction, with little care towards survival
-reptiles -- medium investment in reproduction, with some care for survival
-mammals -- lowest investment in reproduction number, with maximum care in survival

...pg 74

Aging

-the gradual breakdown of the body's machinary

...pg 74

Rectangular shaped age pyramids

-indicate the population is slow growing or not at all

...pg 76

Triangle shaped pyramids

-indicates high birth rates, and a growing population

...pg 76

Demographics

-Cohorts -- specific age groupings in an age pyramid
-10 year old will not reproduce, but a 30-year old has a high chance of reproduction
-10 year old is less likely to die compared to an 80 year old
-These data are helpful for planning resources in society

...pg 76

Baby boomers

-increasing birth rates after WWII, until the 1960s, people had 30% more babies
-ecologists are worried about the bulge

...pg 77

Demographic transitions

-increase in wealth, health, and education naturally decreases birth rate
-This occurs as countries become more industrialized
-higher levels of education employment and health care reduces birth rates
-this will eventually slow down population growth

...pg 77

Biodiversity

-defined as variety among living things, takes three primary forms:
--a diversity of species in a given area
-- a geographic distribution of species populations
--genetics diversity within species population

...pg 82

Ecosystems

-community of biological organisms plus the non-living components with which the organisms interact

...pg 82