Chapter 1 Flashcards
What is DNA made up of?
-made up of nucleotides joined together
Functions of DNA
- carrier of genetic information
- controls cell activities and gives you your traits
What are the 3 parts to nucleotides?
- Sugar - deoxyribose
- Phosphate group
- Nitrogen base (4 of these)
What are the four nitrogen bases? Answer in the pairs they are found in
Adenine (A) paired with Thymine (T)
Guanine (G) paired with Cytosine (C)
Define chromosome
Long strand of DNA which has many genes on it
How many chromosomes do humans have?
46
Define gene
Small strand of DNA and has codes for a particular protein or trait
What is the purpose for DNA replication and when and how does it occur?
It occurs during mitosis so there is a copy of the DNA for the new cell. Steps: 2 strands of DNA separate for replication
Complementary base pairing occurs to form new DNA
Bonds replaced
What are the uses of DNA?
- research for medicines
- gene therapy
- forensics
- paternity test
Define evolution
Theory that groups of organisms change over time to look different from their ancestors
What oxygenated the earth?
Bacteria and algae
What does sexual reproduction do?
Leads to variation
Half of the genetic information from each parent
Differences due to genes found on the chromosomes
Increases organisms chances for survival
Mutations can be passed on by sexual reproduction which drives evolution
Define mutation
A mutation is a permanent change in the DNA of cells
What is the main source of new alleles?
Mutations
If organisms of a species are too similar then they:
- Won’t be able to adapt to changes that occur
2. Could get wiped out by a virus
Define species
A species is an organism that can interbreed and produce fertile offspring and the individual all look similar
Name evidence for evolution
- fossils
- fossil record
- tarpits
- Amber
- flash frozen
- comparative anatomy
- embryology
- DNA
What is a fossil?
Fossils are preserved remains of ancient organisms. They formed when plant or animal matter is changed to stone or the “imprint” is solidified
What is a fossil record?
- collection of fossils that show change within a species over time (history of organisms)
- has gaps in it so it is said to be incomplete (transition fossils are missing)
What is a tarpit?
- once was thick mud where animals had been trapped and died
- teeth and bones have been found in tarpits
What is amber?
-hardened gum or sap of a tree where insects usually will get trapped and preserved
Define flash frozen
Organism quickly frozen in ice
What is comparative anatomy?
What similar structures did the animals have, then lose or gain, compared to animals of today.
Examples are skeletal, nervous, and circulatory systems
What is embryology?
In vertebrates, the early stages of development look very similar with tails and gill slits
- therefore, similar ancestors
- embryology traces evolutionary pathway
What has the same structure for every living thing on earth?
DNA
Which sedimentary rock layers are the oldest?
The deepest layer.
What is the Burgess Shale and where is it located?
The Burgess Shale is the resting place to a vast amount of 530 million year old sea creatures and is located in the Rocky Mountains.
What are two examples of organisms found in the Burgess Shale?
Opabinia and hallucigenia
How many mass extinctions have there been?
5
Why is the Burgess Shale remarkable?
Life forms of half-billion years old remain preserved and almost intact
What is radioactive dating?
Radioactive dating is measuring the decay of radioactive isotopes. Scientists use this method to calculate the ages of rocks and fossils
What radioactive isotope is used to date old fossils over 50,000 years?
Potassium and uranium
What radioactive isotope is used to date young fossils less than 50,000 years?
Radioactive carbon dating
Approximately how old is the earth?
4.5 billion years old
Approximately when did life first appear on earth?
3.5 billion years ago
Define population
A group of individuals of the same species occupying a given area at a certain time
Define phenotype
The observable traits of an organism that arise because of the interaction between genes and the environment
Define genotype
The genes an organism contains
Define gene pool
All of the genes that occur within a specific population
Define allele
Two or more alternate forms of a gene
Define heterozygous
A genotype in which the genes of a pair are different
Define homozygous
A genotype in which both genes of a pair are identical
Define allelic frequency/relative frequency
How often an allele occurs in a population compared to another allele
Define natural selection
Nature determines the organisms that will survive
What are Darwin’s 5 ideas?
- Overpopulation
- Competition
- Variation
- Survival of the fittest
- New species
Define overpopulation referring to Darwin’s 5 ideas
Organisms tend to overpopulate and produce many offspring more than the environment can support. Organisms will reproduce until something stops them (usually food)
Define competition referring to Darwin’s 5 ideas
Because of overpopulation, individuals compete with one another over limited resources like food, shelter, water, and mates. There is a struggle for existence among individuals of a species.
Define variation referring to Darwin’s 5 ideas
Individuals of a population vary in their traits and characteristics. No two are exactly alike. This variation is able to be passed on to offspring
Define survival of the fittest referring to Darwin’s 5 ideas
Those individuals that have a genetic trait which gives them an advantage over others of the same species. This means that the organism has adapted well to their environment.
Define new species referring to Darwin’s 5 ideas
New species results by inheritance of trait(s) or genes that give them an advantage over others. New species evolve.
Define speciation
Where one species evolves in to one or more other species. Also called adaptive radiation.
Define adaptation
A heredity characteristic that provides advantage for survival and reproduction.
What are 3 types of adaptations?
- Structural (speed, camouflage, etc)
- Physiological (maintain internal temperature)
- Behavioural (migration)
What are some examples of natural selection?
- Darwin’s finches
- Peppered moth
- Antibiotic resistant bacteria
- Pesticide resistant mosquitoes
Natural selection acts on a population in 3 ways:
- If the environment favours the average of distribution, the selection is called stabilizing selection
- If the environment favours are extreme, the selection is directional
- If the environment favours both extremes, the selection is disruptive
What are factors that increase genetic variation?
- Mutations
- Gene flow
- Recombination
What is gene flow?
Individuals of different populations immigrate or emigrate between population of the same species. Brings new genes into a population and adds variation to gene pool, new alleles. Gene flow prevents specialization to environment.
What is recombination?
Parts of chromosomes switch parts, crossing over during meiosis
What are factors that decrease genetic variation?
- Natural selection
- Genetic drift
- Non-random mating
What is genetic drift?
Random or chance change in the frequency of a gene. A change in allelic frequency over time due to chance.
What is an example of genetic drift?
A natural disaster could wipe out a large number of animals of a species. Those that survived are able to reproduce not necessarily the strongest or fittest just luck.
What is non-random mating?
Some organisms have more opportunity to mate than others and therefore produce more offspring (and more copies of their genes).
Has more desirable trait.
What are two reasons for non-random mating?
- simply easier to mate with a nearby individual rather than one further away
- competition for mates occurs among animals = active selection of mating partner (not random)
What is convergent evolution?
Evolution towards the same type of adaptation among different groups of organisms.
What does convergent evolution produce? (Structure wise)
Analogous structures which have the same function but different structure.
What is an example of convergent evolution?
Flight: wing of an insect and wing of a bird, both are used for flying but each has a very different structure
What is divergent evolution?
Evolution which led to different body parts developing from an original body plan
What does divergent evolution produce? (Structure wise)
Homologous structures which have a different function but same structure due to a common ancestor
What is an example of divergent evolution?
Forelimb of mammals: Same bone pattern but each limb is specialized to the animals way of life. Human-grasping (hand) Whale/dolphin-swimming (flipper) Bat-flying (wing)
What does divergent evolution lead to?
Speciation
What are vestigial structures?
Remnants of a structure that had a function in an ancestor but no longer in the evolved organism
What are some examples of vestigial structures?
Appendix-used to be for digestion
Tail bone
Snake hips-pelvis bone but no legs
Chickens have gene for teeth but no teeth
What causes phenotypic variation?
Mutations, gene flow, and recombination
How is phenotypic variation related to natural selection?
It decreases variation
Define gradualism in terms of evolutionary change.
Evolutionary change that occurs slowly and constantly over time. Based on evidence from the fossil record where some organisms have evolved slowly (in geological time) examples are sharks, crocodiles, cockroaches, and horseshoe crabs
Define punctuated equilibrium
There is a period of stability, where little change if any, occurs. However, this is followed by periods of rapid change to a species of plant or animal. Caused by environmental condition such as a nice age. Some species will die off but others will need to change quickly and adapt to new environments therefore rapid evolution. Animals with higher reproductive rates are better able to adapt. Ex: mammals and birds
Define endangered species
Wild species with so few survivors that the species could soon become extinct. Examples: Douglas fir, pandas, snow leopard, whales, and polar bears
Define extinction
Complete disappearance of a species from the earth. Stops the evolution of that animal. Leaves niches open for other animals to fill. Increase speciation of other organisms.
Ex: dodo birds, dinosaurs, wooly mammoth, Tasmanian wolf
What are factors causing extinction?
- pollution
- climate change
- hunting/poaching
- invasive species
- loss of habitat
- speciation
Define evolution in genetic terms
Evolution can be defined as a change in the relative frequency of alleles in the gene pool of a population. Mutations are main source of new alleles. Some kind of reproduction has to occur to pass on the mutation.
Scientists notice that individuals in a plant species are growing taller with each generation. Explain what is happening to the gene pool of this population.
Natural selection occurring. Desirable trait allele is used for advantage. Allelic frequency is going up. Tall gene more common then short one.
Where is DNA found?
In the nucleus and never leaves
What are individual nucleotides held together by?
Hydrogen bonds between the bases to form a chain of DNA
