Studied by 7 peopleTags & Description
START OF GENETIC UNIT
What is DNA coposed of?
5 Carbon Sugar (Deoxyribose), Negatively charged phosphate group, a nitrogenous base
What are the 4 nitrogenous bases?
Adenine, Guanine, Cytosine, Thymine
What is the difference between Primidines and Purines?
Purines are Double Ringed while Pyrimidines are single ringed
What is Chargaffs rule?
Always hydrogen bonds betweeen base pairs. 2 Between A-T and 3 Between G-C There is two sugar phosphate backbones
Describe the DNA replication process
Unzipping: H Bonds are Broken
Base Pairing: Free nucleotides that come from food and nutrients that we consume
H Bonds Reform: Reformed H Bonds
Why do Cells need to divide?
Restriction with Diffusion: If the cell gets too big it can no longer diffuse nutrients properly nor lose waste
Restrictions with Command Control: One nucleus is incapable of controlling a cell if it’s too big
Restrictions with SA to V Ratio: SA = A of All Faces V: lwh The surface area to volume ratio will get smaller. THis means that the volume is growing faster than the surface area which requires more nutrients but cannot get it because of the lack of surface area to absorb
What is the funtions of mitosis?
To allow growth for a multicellular organism
To allow repair for damaged cells
To replace dead cells
What is DNA?
Deoxyribonucleic Acid, double helix of S-P backbones
What is Chromatin
Long thin strands of DNA scattered through the nucleus
What is a chromsome?
Coiled, condensed, replciated strands of chromatinW
What is a chromatid?
One half of the replicated chromsoome and two sister chromatids are indetical
Explain Prophase in Mitosis
Chromosomes coil & condense
Nuclear membrane disappears
Two pairs of centrioles move towards the poles and genetre spindle fibres
Explain Metaphase in Mitosis
Spindle fibres attached to centromemere
Allign in the middle
Explain Anaphase in Mitosis
SPindle fibres shorten and pull sister chromatids apart to oppsoite poles
Explain Telophase in Mitosis
Chromosomes begin to uncoil & produce chromatid
Spindle fibres disappear and nuclear membrane reappears
Pinch in the middle for cell division
Explain Cytokinesis in Mitosis
New cytoplasm is formed
What is the purpose of Meiosis
produce gametes that each contain 23 chromosomes.
What is Gonad Cells?
(Reproductive Cells)
23 homologous pairs
What is the difference bteween diploid and haploid?
Diploid cells (2n) are cells that contain pairs of chromosomes while haploid cells (n) are only one member of each pair.
What is Interphase I
DNA replicates, homologus pairs beigin to migrate towards eachother
What is Prophase I
Centrioles & Spindle fibres appear and synapsis
The procress of synapsis is where they warmthemselves around eachother (crossing over) where segements of non-sister chromatids are exchanged
What is Metaphase I
Tetrads line up in two rows, randomly. Independent assortment means that chromosome five from mom mayu be in left column while father might be to the right
What is Anaphase I
Tetrads are pulled apart as the spindle fibres shorten
Variation in Prophase/Metaphase causes in variation in the gametes
Telophase I
Chromosomes reach poles and cells split two cells present
Interphase II
Rest phase
Prophase II
Centrioles and spindle fibres reform
Metahphase II
Chromosomes line up at the equator
Anaphase II
Chromatids seperate as the spindle fibres shorten
Cytokensis II:
Chromosomes reach the poles, nuceoli and nuclear membrane. 4 haploid cells each containing 23un replicated chromosomes
What is Heredity
The study of how traits are passed from generation to generation
What is a gene?
A part of the chromosome and it expresses traits by producing specific proteins.
What is an allele
Egg and sperm cells donate one set of chromosomes. Defined as the form a gene can take
What is Homozygous
2 alleles are the same
What is heterozygous
2 alleles are different
Genotype vs Phenotype
Combination of letters = genotype and pheatures = phenotype
What are punnett squares?
Shows the alles in the parents gametes along the top
What is amonohybrid cross?
Single trait, 1:1 Phenotypic / Genotypic Ratio
What is a dihybrid cross?
Two traits, Pheno 9:3:2:2, Geno no ask
Simple / Complete Dominance
Dominant allele will block out the recesssive allele
Incomplete Dominance
Prime symbol used, one allele doesn’t mask the other. Known as alleles that are blended
Codominance
Superscript used, heterozygote fully exxpressed
Mulitple Alleles - Blood
ABO blood type, Rh factor (protein that is found on the red blood cell
What is sex linkage?
X linked recessive traits are not fullyr elated to the feminine body characteristics
What are pedigrees
Shows mulitple generations of a genetic trait. Males = squares and females = circles Shaded symbols = affected half shaded carrier, unshaded is affected. Horiziontal line between man adn woman resprent marriage/mating
Start of Evo
Who was Malthus?
A demographer that wrote “Essay on the Principle of Population” He also stated that factors that would limit human population, aka population “checks” create gaps where the weak die out and the strong live.
Who was Wallace?
An optimisitc writer who coined “struggle for existence” and developed that the “fittest would survive” He believed that over generations natural selection of inheirted traits could rise to new species
Who was Lyell?
A geologist who sugessted that rather than ~8,000 y/o the Earth was 100s of millions of years old. He stated that the formation of the Earth’s crust took place through countless small changes over vast periods of time.
Who was E. Darwin?
The grandfather of Charles Darwin, he was a physician and philosopher. He believed that “Everything from shells” meaning all organisms evolve from simple to complex . Partially true as all organisms become more complex overtime because they adapt through natural selelction.
Who was C. Darwin?
Often acredited to developing the theory of Evolution, he coined the term natural selection. He published “On the Origin of Species by Means of Natural Selection” where it explains how natural selection occurs and that new species come from pre-existing species as they all share a common ancestor.
What is a Fossil Record?
deceased organisms preserved in rock; compressed over millions of years, so older fossils are found deeper than younger ones
Hole In Fossil Record?
gaps where fossils explaining likely links between species are missing
What are analogous structures?
Analogous structures are two unrelated structures that have a comparative purpose and Same traits evolved by different species that do not share a common ancestor
What is convergent Evolution?
unrelated species develop similar traits for the same purpose
What is Vestigial Structures?
Body parts that once performed an important function that have been reduced to or incompletely developed structure.
What are Homologous Structures?
Similar physical features in organisms that share a common ancestor, but features serve different functions
What is biogeography
How and When species may have evolved. Distrubution of life forms across geographical regions as a result of plate tectonics and habitats changing
What are the DNA similarities?
% of genes/DNA thar organisms share records to similarities
Artifical Selection
Indentification by humans of desirable traits
What are Ring species
Illustrate what happens over time as poplation genetically diverge. Pockets of overlapping species are able to interbreed, but if they converge they cannot
What is compartive embyrology?
Study of embryos to indetify similarities and differences bteeween species
What are HOX genes?
Similar genes in organisms the formation of body structures in early embryonic development.
What is resistance?
When germs develop the abilkity to dtect the drugs designed to kill them
What is the formula X = (1/4)^n stating
N is the number of genes that are difference, x will represent the proportion of F2 that look like parents
What is Natural Selefction?
A procress where random variation within INDIVIDUALS are selected for by nature in a NON-RANDOM way.
What does Natural Selection Result in?
a population of organisms changing over many generations
What are selective pressures?
Result of abiotic or biotic factors that put pressure on a population
What are mutations?
Changes in the DNA (genetic material) that result in new forms of genes (Alleles).
What is the only source of new genetic variation?
Mutations are and they are random and continous
When are gene mutations?
Genes mutations occur during DNA replication
When are chromosomal mutations?
During Meiosis
What is selective Advantage?
Characteristic that enables it to survive and reproduce better than others in a population in a given ennvironment
What is variation?
Variation is the different DNA among individuals/populations. The variation in a species that creates a range of successful/unsuccessful gene
Adaptations - Behavioural
Affects the organism naturally due to a new predator or new environment
Adapations - Physiological
Adaptations that involve a physical aspect that cannot be seen in their appearance, an example would be hibernation
Adapatations - Structural
Visible aspect of the organism. Two common examples are mimicry; where a harmless species resembles a harmful one or camoflage; colouration to avoid being preyed on
Variation - Conclusion
Mutations cause a new gene combination that result in variations and adaptations. Natural Selection will then “feeds on” these variations and will select for the best adapted individuals
Natural Selection
Does not anticipate changesi n the environment, it is the result of variety of selective forces
Mutation → Natural Selection
Mutation → Variation/Adaptation → Selective Pressure → Natural Selection
What rule does Genetic Drift Break?
Population is Very Large Rule
What is Genetic Drift?
Change in frequency in alleles of an existing gene variant in small populations due to random change. T
Why does Genetic Drift impact smaller populations the most?
by leading to the fixation of alles, and reducing it’s genetic diversity
What is the Founder Effect?
Reduction in genomic variability that occurs when a small group of individuals becomes seperated from a large population
What is bottleneck Effect?>
When a population is greatly reduced in size, which limits genetic diversity of species because only a small part survives
What rule does gene flow break?
No migration rule
What is gene flow
When genes transfer from one population to another. (MIGRATION)
What rule does sexual selection break?
Mating opportunities are equal
What is sexual selection
Favours a trait that influences mating success
Female choosing mates
Most colorful
Male Vs Male Competition
Males defend a terriotry against other males
What is sexual dimorphism
When the male and female counterparts look different
What rule is broken from Patterns of Natural Selection
No Natural selection + No mutation
What is directional selection
Individuals with more extreme traits are favoured
What is stablizing selection
Stable seltive pressures staht are long term
What is disrusptive selection
Variations at opposite extremes
What is cumulative slelection?
Complex organisms arise and favourable mutations build up over time
What rule does artifical selection break?
random mating
What is artifical selection
When a human chooses an organisms genes that can be passed down
5 conditions of H-W
Population is Large - Fluctuations can change allele frequencies
Mating Opportunities are Random - must pair by chance
No Mutations - New alleles may occur creating new frequencies
No Migrations - Remove alleles from one population and add to the other
No Natural Selection - Equal Allele chance
Note
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