Exam #4 Flashcards
o Diploid
– 2 parts, 2 each chromosomes - cell containing 2 homologous sets of chromosome 2 chromosomes on each type 2 copies chromosome # 1,2 etc 22 homologous pairs Xy – sex chromosomes
o Gene
Part of DNA molecule that governs a specific trait
o Alleles
An alternative form of a gene
Cellular genetics
- Traditional/mendelian genetics
Gene inheritance background
- monk working with pea plants
- mathematically worked out the manner in which traits (genes) were passed from one generation to the next
MENDEL’S EXPERIMENTS
Studied seven characteristics:
Seed color,seed shape, flower color, pod color, pod shape, flower position, stem height
- Yellow, green – 2 versions of each
Mendel started with true breeding plants and then crossed these with each other to find different offspring
- Same color with same color = same color true breeding
- start with true breeding – only white or purple
o Crossed them
All offspring had purple flowers First generation
• Crossed them with themselves F2 generation
o ¾ of plants have purple flowers and ¼ plants have white flowers
o Hundreds of plants
o Did all same traits – same relationships
- start with true breeding – only white or purple
Mendel’s Assumptions:
Each characteristic is governed by more than one factor
These factors are passed from one generation to the next
Only some of these factors are ever observed (expressed)
Gametes only carry one factor for each characteristic
Factor
- allele
MENDEL’S LAWS
Law of Segregation :
Law of Independent Assortment:
Law of Segregation :
Each trait (gene) has 2 factors (allele)
Factors segregate during reproduction
Only one factor for each trait ends up in the gametes
Fertilization gives each individual two factors
Law of Independent Assortment:
Each pair of factors (alleles) assorts independently of the others
o segregates itself independent of other factors
All possible combinations can occur in all the gametes
o could have short plants with white flower green seeds – 7 traits all assorted themselves independently – all combination on all those characteristics
Each of the two alleles found at the same locus
are dominant or recessive
Dominant alleles
are expressed regardless of the nature of the other allele (heterozygous)
Recessive alleles
are expressed only when both alleles are the same (homozygous)
Genetic notation
Dominant alleles are usually written as a capital letter
Recessive alleles are usually written as a small case letter
These can be written together to denote the genotype of the individual
Modern Understanding
Mendel’s factors are the genes found on the chromosomes. They segregate because of the formation of haploid gametes (meiosis)
Genes for various traits are found on different chromosomes and so there are all combinations found in gametes.
3 situation 3 characteristics of genotype
- Homozygous dominant
- Heterozygous
- Homozygous recessive
genotype
the genetic content of the organisms including all the allele variations:
homozygous: dominant, recessive
Heterozygous
Phenotype
- the observed trait of an organism
- heterozygous and homozygous dominant genotypes will express the dominant trait (they look the same)
what did mendel get wrong
- P a B – all stay together
- Will not assert themselves independent of each other
- Has to be in different chromosomes – the different characteristics
Alleles
: different versions of the same gene found on homologous chromosomes at the same locus
Alleles are dominant or recessive to each other :
Dominance
: the version of the gene is expressed regardless of the other allele
Recessive
: the version of the gene is expressed only when the other allele is also recessive
Punnett squares
Method to figure out the results of genetic crosses
Monohybrid : crosses using only one trait
Dihybrid : crosses using two traits
Somatic and Sex-linked traits
In many organisms gender is determined by the possession of certain chromosomes : sex chromosomes
Genes located on these chromosomes govern sex-linked traits
Genes on the other chromosomes are somatic traits.
- Homo sapiens - chromosomes
o 22 homologous pairs of chromosomes
Somatic chromosomes
Characteristics – refer to as autosomal traits
• One that is governed by alleles found in somatic chromosomes
• Dominance vs recessive
o Always hold true
o Dominant trait will be expressed regardless what other allele is
o 1 pair of sex chromosomes
Non-somatic chromosomes
Not homologous
Characteristics found on sex chromosomes – sex linked traits
Characteristics found on sex chromosomes – sex linked traits
• XX – females o Dominant vs recessive o Same type of gene found in loci • XY o Non homologous pchromosome o Dominant expressed o Recessive Expressed o Both – doesn’t matter where it is..theres no corresponding allele to over ride it. All will be expressed
Incomplete dominance
Heterozygous genotypes show a intermediate phenotype (different phenotype) Snapdragon flower color o Red flowers – homozygous dominant RR Red Rr (pink) dominant not complete o White flowers – homozygous recessive Rr White Camellia flower color
Codominance
Alleles which are equally expressed Examples : human red blood cell type A B AB O - Two dominant version – can be both expressed
Blood types determined by protein presence
- Blood determined by proteins on surface of RBC o 2 version of protein A – dominant traits B – dominant traits o If no proteins on surface of cells O blood cells • Recessive • Homozygous recessive to have characteristics
Phenotype of Blood and its antigens
o Proteins – antigens A type = A antigens B type = B antigens AB type = AB antigens O type = neither AB antigens
blood type and antibodies
o Antibodies – floating around blood anti bodies against that’s not suppose to be there A = anti B B = anti A A + B = No antibodies O = has both aA and a-B bodies
o Genetoypes of Phenotype
A = AA, Ao
B = BB, Bo (Homozygous dominant, heterozygous)
A+B = AB (both dominant) Codominant Genotype
O = oo (homozygous recessive)
o Compatibility of blood types
A = A, O Transfusion based on matched blood type B = B, O A+B = A,B,O • Universal recipient • Rarest bloodtype • codominant O = O • Compatible as a donor to any bloodtype • Universal donor
Polygenic traits
Phenotypes governed by more than one gene (more than one locus)
Iris color
Human skin color
- Most visual characteristics appear in human
- That char is governed by one gene in more than one locus
- Represents in more than one chromosomes
- Hair, skin, eye color
Genetic disorders
- Mutations in the DNA
Autosomal
Tay-Sachs o Autosomal recessive disorder o Both version of allele as recessive trait Cystic fibrosis o Recessive traits PKU o Dominant o Doesntn process protein very well Neurofibromatosis o Single mutation – Dominant Huntington’s disease o Dominant trait
Genetic Disorder
Sex-linked
Hemophilia
Hemophilia Inability of blood to clot – bleeders Delecate blood vessels Carried on X chromosome X(H) Xh females Alexis – male • Xh Y
Genetic Disorder
Sex-Linked
Color-Blindness
Color-blindness X(N) normal X(n) recessive Female – both version XN Xn(normal) • Xn Xn must carry mutation color blind • Father has to be color blind • Recessive must have both the gene • All sons will be colorblind • Daughter not nescessarily Male • XN Y normal • Xn Y colorblind o Carried in X chromosomes
Non-disjunction
Chromosomes don’t separate (what stages?)
Gametes have too few or too many copies of the chromosomes
Trisomy 21
Three copies of this chromosome
Klinefelter’s
XXY
Mutations shows up in organism
o Extra, missing, changing sequence of basis
o Result of poor cell division – non-disjunction
- Instead of separating – chromosomes stick together
some gametes with too few chromosomes – with too many chromosomes
• Too few – don’t survive no longer humans, missing something
• Result of other has one too many
o Trisomy
Three copies of this chromosome Trisomy 21 • Downsyndrome • Has 3 copies of chromosome 21 • Shows up more often in offspring of older women o First pregnancy o Over 40 • Correct spindle/apparatus governs mitosis
o Klinefelter’s
Don’t have division of XX chromosome
XXY (m)
Not very male like, underdeveloped genital,, steriless
Central idea of biological science is?
– evolution: both commonalities and how things become different/diversity
Earth is estimated to be about?
4.6 billion years old
The earliest evidence of life is from?
3.5 billion years ago
NATURE OF THE EARLY EARTH
The surface of the early earth was primarily volcanic and thought to have been very hot.
The earth has always been of sufficient size to have an atmosphere but the composition of the atmosphere has changed dramatically from the primitive earth to now.
- Atmosphere about 1/5 oxygen today wasn’t back then no free oxygen
- Has to be sufficient size to hold on to gravity
PRIMITIVE ATMOSPHERE
Water vapor, nitrogen, carbon dioxide, hydrogen and carbon monoxide, ammonia, methane.
- Simple gasses
NO free OXYGEN
The atmosphere back then was? unlike todays
The atmosphere was a reducing atmosphere not a oxidizing atmosphere like today.
THE FIRST BIO-MOLECULES
- How did it first combined into cell – bio chemicals
- 1950s – miller’s experiment
o Amino acids found (building blocks of proteins) -> enzymes -> regulates other reactions
Polymerise – formed chains
Produce biological active molecules from inorganic starting material
The first Bio-molecules
- the action of primal forces such as? on molecules in the atmosphere created organic molecules like amino acids the building blocks of proteins
Heat of volcanoes
the electricity from lightening
radiation from the sun
Because of lack of O2 in the primordial days there was? compared today
- increase amount of radiation from the sun – high amount UV radiation
Now - Because of high O2 – part of it converted to ozone
o Buffer agains UV radiation
If it shrinks or disappears increased amount of radiation - UV radiation has an effect to biological DNA, RNA
The First Bio-Molecules
- newly formed organic molecules accumulated over hundreds of thousands of years and started to polymerize into larger?
Macromolecules
- polymers of amino acids or other nitrogen containing compounds
Theories of why – which came first – how life developed – probably combination of both
Protein world
- Amino acids can be generated abiotically (without any organism being around)
o Polymeration can happen without living things
Development of enzymes
(requirements of living things – reproduce)
Don’t have ability to reproduce
RNA World
o Can copy itself
o Some piecies have enzymatic activity
Can cut themselves in two
o More difficult to make abiotically
Alternate Hypothesis of the first active bio-molecules
RNA molecules formed would be able to begin enzymatic action on itself (some RNA molecules demonstrate this trait)
Proteins formed first would have some catalytic properties (enzymatic)
PROTOCELLS
protobionts
- Formation of primitive cells-like structures happens spontaneously under the proper conditions.
- Phospholipids spontaneously form liposomes in aqueous conditions. These are droplet-like bodies which have been made to contain different kinds of substances like certain drugs.
- If have certain lipids in a solution – lipids will form as a cell like structure in environment principally of?
water
o Bodies of water – condition that will allow cell like structure to happen
o Example: phospholipids
Not impossible to be produced in abiotic
As a way to process drugs (scientist)
In order for true cells to emerge, what must happen?
proteins (enzymes) and some sort of nucleic acid needed to combine to form a metabolizing and reproducing cell.
The first cells were most probably
anaerobic heterotrophs feeding off small organic compounds. Recently, such organisms have been found at the bottom of the sea feeding off of inorganic materials spewed from the earth’s interior.
Cell evolution
Development of complex cell forms might have been the result of
- symbiotic relationships between simpler cells
Eukaryotic organelles (chloroplasts and mitochondria) have their own DNA
These might have been simple cells engulfed by larger cells
Functioning cell has to have proper condition
- Some sort of genetic material (doesn’t have to be DNA, could be RNA)
- Some sort of enzymatic activity provided for by RNA, proteins or both
- Have to have condition in which package can duplicate itself
- (all of this happening devoid of oxygen which means not photosynthetic)
o Single cells feeding off organic material (heterotrophic…?) not need oxygen to metabolize
o Found at bottom of see where theres no light
o Simple bacteria have very simple type of metabolism feeding off inorganic material
o Simple heterotriphic anaerobic
First cells and - The Endosymbiont Theory
- Simple bacterial life cells
- Development of more complex cell is due to symbiotic relationship between this cells
o Involves parasitic relationship (engulf eat other one) engulf persist inside cells and endures - Bacteria
o DNA
o - Eukaryotic cells
o DNA composed differently/structure different
o Organelles like mitochondria and chloroplast have their own dna
Separate and distinct from cells nuclear DNA
Looks and like act bacterial dna
o Heterotrophic engulfs another one maybe anaerobe aerobe
If engulf organism resist digestion then persist in cell
Overtime develop mutually beneficial relationship
Loses some of its genetic characteristics (both)
EVOLUTION of LIFE on EARTH
Evolution is
the process by which all the variations of life on earth came into being.
Evolution explains
why there are so many different forms of life and at the same time explains how those forms are connected, how there is a unity of life on this planet.
Evolutions of the cell
Chemical evolution
Primitive Earth -> (cooling) -> gases -> (energy capture) -> small organic molecules to both macromolecules and plasma membrane (with polymerization) then both to -
Biological Evolution
Protocel -> cell -> to both Photosynthesis and aerobic respiration
Aerobic respiration didn’t evolve until photosynthesis
Our present understanding of evolution comes
from an examination of animal behavior and from the records of fossils.
Fossils are
remains of living organisms left when an animal dies. These remains have been preserved and have, over long periods of time become rock-like. This happens only when the normal decay processes are prevented.
Where are Fossils are found?
embedded in rock layers which can be dated through various chemical analyses.
Fossil are then are as old as the rock layers in which they are found.
led to Geological milestones
First Eukaryotic cells
2.1 billion years ago
First vertebrate animals
500 million years ago
First dinosaurs
260 million years ago
First mammals
230 million years ago
Last Dinosaurs
65 million years ago
First humans
2 million years ago
24 hour earth clock
- Earth forms at midnight
- First known rocks form at 3 am
- First prokaryotic single cells form at 5 am
- free oxygen doesn’t appear in the atmosphere until 1pm
- First eukaryotic cells form at 4pm
- First multi-cellular organism form at 8 pm
- dinosaurs appear at 10:30 pm
- Man first appears at 30 seconds before midnight
Process of evolution
- evolution is propelled by the following forces:
- population genetics: changes in genetic make-up of a population
- natural selection: environmental forces on the gene pool
- speciation: development of new populations
Population genetics :changes in genetic make-up of a population
What happens to genetics of entire population
Evolution does not affect an individual; it happens in population
Changes in genetic population
Natural selection : environmental forces on the gene pool
Another force that drives evolution
What Darwin talked about
Artificial selection
Speciation : development of new populations
Another driving force in evolution
Development of brand new population
Brand new genetically distinct groups of organism
Modern Homo sapiens
- Genetic mixture of number related species
- Only species of homo that exist now
o Had homo neanderthalensis
o Homo erectus
o Homo habilis
o All are ancient cousins that have contributed genetic makeup to us
Use to be thought as dead end
Some part of homo sapien geno – there are Neanderthal genes
How first organisms evolve and change into myriad of organisms in face of planet
- Evolution
o Genetic change over time
o How genetic characteristics of orgamisn change over time - Longterm or short term same forces at work
Fitness:
physical or behavioral characteristics that enable an individual to survive and reproduce.
o Pass on genetic makeup to offspring (another generation)
Variation :
traits which vary among individuals within a population.
(o Traits among population like population that are different (heights, weight, color – eye hair))
Gene pool :
the total number of alleles available for reproduction within a population.
((o As a population are all of the gene/allele that are available to reproduce
o Not part of gene pool: natural green hair
o Those alleles that can be passed on))
Diversity :
the inheritable variations among a population
((o All of the inheritable distinction within these population (whether expressed or not)
o Has to do with inheritable variation
o Compare with one population to another))
Adaptation
: characteristic which enables individual to survive and reproduce under specific environmental stresses
o An individual = characteristics phenotypes which enable individual to pass same characteristics to next generation
o Environmentally determined – considered as adaptation (skin color)
Population Genetics
Studies of the frequencies of a certain allele within a group of individuals (population)
Predictions about evolution (changes in gene pool) indicated by Hardy-Weinberg Law
Hardy-Weinberg Law
Describes conditions under which the gene pool will not change : that is no evolution will occur.
No mutations : no changes in alleles
Mating is completely random : mating is not based an phenotypes
No genetic drift : large populations where gene frequencies don’t change
No gene flow : no alleles leave the population (emigration), no new alleles enter (immigration)
No natural selection : no environmental forces favor one genotype over another
Natural selection
Environmental forces upon the gene frequency within a population
Mutations
Non-random mating
Genetic drift
Gene flow
Natural selection and man
Man has been practicing artificial selection with domestic animals ever since he started domesticating animals
Natural forces act in the same way over long periods of time on all living creatures.
o Naturally forces that pick the strongest the most fit to succeed to produce more offspring
o Charles Darwin
Observed similarities between living and fossil organisms an diversity of life on the Galapagos islands
Darwin’s Theory of Evolution
Requirements of Natural Selection :
Variations
Inheritance
Differential adaptedness
Differential reproduction
Types of Natural selection
- natural selection can alter variation in a population in three ways
Stabilizing selection
Directional selection
Disruptive selection
Developed theories of natural selection as the force generating all the diverse life forms on earth with Alfred Wallace
• Proposed natural selection as the mechanisms of evolution
• Impact of environment over survival of species
• Observed that
o organisms produce more offspring than the environment can support
Greater potential for variation to reproduce themselves
o vary in characteristics than can be inherited
dog not interbreed with wolf
evolution – not longer genetically compatible – fox , jackal, coyote, dog, wolf from ancestral canine
Speciation
Isolation - Premating - Habitat - Temporal - Behavioral - Mechanical Postmating - Gamete - Zygote - Sterility - Fitness
Speciation
Allopatric speciation
Sympatric speciation
Parapatric speciation
Adaptive radiation
Development of different species in response to different environmental pressures :
Galapagos’ finches
Coevolution
the theory of coevolution involves the interdependent evolution
- a process of mutual selection and adaptive response Within a grouping of species that leads to properties unique to the system
interdependent evolution
development of two (or more) species having a direct ecological interaction
The components of the coevolution systems are the?
symbiotic species
The two main categories of symbiotic species are?
mutualistic and parasitic
mutualistic system involves?
benefit to both ( or all) species involved, and is thought to provide a competitive advantage over that of its members operating independently
A parasitic system involves?
benefit to one of the species, while the other (the host) is harmed by the interaction
- in a properly functioning parasitic relationship, the parasite lives off the host population without eliminating it
co-evolution examples
acacia and psuedomyrmex
flowering plants and insects
modern evolutionary changes
Antibiotic resistance in bacteria
- multiple drug resistance accumulated over time
Evolution
Genotypic changes accumulated over long periods of time due to genetic changes. These changes have generated the diversity of life on Earth.
In the century prior to Darwin
The study of fossils suggested that life forms change
Geologists proposed that a very old Earth
Is changed by gradual processes
While on the voyage of the HMS Beagle in the 1830s
Charles Darwin observed similarities between living and fossil organisms and the diversity of life on the Galápagos Islands
during the Voyage of the HMS Beagle 1831 - 1836, Darwin…
Darwin proposed natural selection as the mechanism of evolution
Darwin observed that organisms
Produce more offspring than the environment can support
Vary in many characteristics that can be inherited
Fossils :
Mineralized remains of living organisms
- fossils and the fossile record strongly support the theory of evolution
Darwin reasoned that natural selection
Results in favored traits being represented more and more and unfavored ones less and less in ensuing generations of organisms
Darwin proposed that living species
Are descended from earlier life forms and that natural selection is the mechanism of evolution
Scientists can observe natural selection in action
Camouflage adaptations that evolved in different environments
- development of pesticide resistance in insects
POPULATION GENETICS
Populations are the units of evolution whose individuals can interbreed and produce fertile offspring
population
is a group of individuals of the same species living in the same place at the same time
population genetics
studies how populations change genetically over time
A gene pool
Is the total collection of genes in a population at any one time
Microevolution
Is a change in the relative frequencies of alleles in a gene pool
Hardy-Weinberg equilibrium
- States that the shuffling of genes during sexual reproduction does not alter the proportions of different alleles in a gene pool
- Defines conditions under which gene frequencies don’t change, that is there is no evolution
For a population to be in Hardy-Weinberg equilibrium, it must satisfy
five main conditions The population is very large The population is isolated Mutations do not alter the gene pool Mating is random All individuals are equal in reproductive success
EVOLUTION FORCES
genetic drift
gene flow
natural selection
Genetic drift
Is a change in the gene pool of a population due to chance
Can alter allele frequencies in a population
Can cause the bottleneck effect or the founder effect
Gene flow
Is the movement of individuals or gametes between populations
Can alter allele frequencies in a population
Natural selection
Leads to differential reproductive success in a population
Can alter allele frequencies in a population
Stabilizing selection
Favors intermediate phenotypes
Directional selection
Acts against individuals at one of the phenotypic extremes
Disruptive selection
Favors individuals at both extremes of the phenotypic range
Genes
- Eukaryotic cells
- Most organisms exists in normal state as
Diploid cells
Natural selection
- More accurate to describe it as Non-survival of the least fit
o Least camouflage, easier to be seen, unable to hide themselves, not passed down to subsequent generation - Environmental condition acts upon phenotype of the population
o Why recessive gene stick around in population
Recessive gene not acted upon by environment because its not expressed
Ketlewell’s moths
- Naturalist 1800 england
- Peppered wing moth
- Hangs out in forest in England –
- Every so often black winged mutant
o Birch forest
o Get eaten more often by birds - If you can see – catch it and eat it
- Industrial revolution – coal, steam powered everything
o Generate soot – in air
o Blackened trees
o Moth black now because white easily eliminated
o Genetic change of population of group of moths from peppered wing verstion to black version because of environmental condition - Changes in phenotypes of population purely dependent upon environmental condition
o Natural selection
- Adaptive radiation
o Development of different species in response to different environmental pressures:
o Development of different species from some common ancestors
Coevolution
- Development of two or more in response to the same set of natural selective forces
- Process of mutual selection (dif pop interacting with each other)
- Adaptive response (generation after generation is a response to the same environmental forces)
- End up with a symbiotic relationship
Isolation
o isolated from species
Premating
Has to do with physically isolating one group from another
Habitat
• 2 different species don’t breed don’t exist in same habitat: tigers and lions
• Physically/geographically isolated by habitat
Temporal
• 2 dif organisms separated base on time the function
• Insect only moves around at night..only daytime..temporally isolated
Behavioral
• Song birds – sing to attract mate – only that bird that is responsive will respond
• Learned wrong song
Mechanical
• Can’t fertilize each other – bear and Chihuahua – physically impossible
Isolation
o isolated from species
Postmating
Gamete incompatibility • From human and fish = incompatible Zygote • Inviability • Do fuse but resulting zygotes doesn’t have sufficient genetic material to develop into a fetus Hybrid Sterility • Liger • Resulting hybrid – cant reproduce o Horses and donkeys = mules cant reproduce Hybrid Fitness • Lack of • Leopard and cheetah – Africa savanah o Occassionaly hybrid Not nearly as fit in that environment than either parents Cant find place well adapted to
Allopatric speciation
o The result of habitat isolation
Sympatric speciation
o Development of new species within an already existing population
o More plants than animals
o Plants can self fertilize/pollinate
o Mutation in individual cant breed with any other keen but by itself
Development of different population – new species within existing one
o Result of some mutation that occurs/changes the fertility requirement of that particular individual
Parapatric speciation
o The result of hybrid that occurs where two species overlap
o Development new species/hybrid in habitat overlap
Geographical, temporal overlaps S1 with S2 = Hybrid zone
• Hybrid only interbreeds with hybrid = brand new species
Peripatric speciation
o Fringe habitats
o Development of new species on the fringe of a habitat
o Forest – end – give rise to prairie
- Two competing ideas of grand scheme of evolution
Phyletic gradualism vs. punctuated equilibrium
- Evidence based
Phyletic gradualism
- Gradual transition from some common ancestor to a new species
- Assumption we should see evidence of transition – fossil; living organism
o Fossil records = doesn’t give that evidence
For very long period of time number and kind of species embedded in that particular fossil are the same
Species are pretty stable for long periods of time
• Stays/maintained isolated
- Punctuated equilibrium
Period of species equilibrium and period of time development of new species
- Fossil record points to this
o Cambrian explosion
