Test 2(2 Flashcards
What functions do proteins have?
Enzyme and structural purpose, determining our traits
Are proteins built directly from DNA?
No.
What is RNA?
Ribonucleic acid, a nucleic acid made of nucleotides.
What is the structure of RNA?
Single helix
In how many ways does RNA differ from DNA?
Three.
Which five carbon sugar do RNA nucleotides contain?
Ribose (instead of deoxyribose like DNA.)
What is the difference between deoxyribose and ribose?
Ribose contains one more oxygen then deoxyribose.
What is the difference in nitrogenous bases between DNA and RNA?
They both contain adenine, guanine, and cytosine, but instead of thymine like DNA, RNA contains uracil, complimentary to adenine.
Transcription
The process by which a gene’s instructions for making proteins are transferred to an RNA molecule.
Where does transcription occur?
The nucleus, where the DNA is located.
RNA polymerase
An enzyme that binds complementary RNA nucleotides during transcription.
What is the first step of transcription?
RNA polymerase binds to a special start sequence of DNA.
In transcription, what does the RNA polymerase do after binding to the special start sequence of DNA?
It unwinds and separates the two strands of the double helix.
In transcription, what happens after the RNA polymerase unwinds and separates the double helix?
It adds and links complementary RNA nucleotides as it reads the DNA.
What base pairing rules of DNA does transcription follow?
All of them except that in RNA uracil pairs w adenine instead of thymine pairing w adenine.
What does transcription proceed until?
RNA polymerase reaches a stop sequence of bases that marks the end of a gene.
What happens after transcription is completed?
The two strands of DNA close up, reforming the double helix and the RNA strand separates from the DNA.
What are the practical differences between transcription of RNA and DNA replication?
- One strand of RNA is produced vs. two strands of DNA
- In DNA replication, both strands of DNA are used as templates vs. in transcription only one strand is used
What can be formed by transcription?
Different types of RNA.
What is mRNA?
Messenger RNA, which carries the instructions for building a protein from the DNA gene to the ribosome.
What happens w mRNA at the ribosomes?
The instructions are “read” which code for specific amino acids
What do many amino acids joined together make?
A protein
Codons
Series of three nitrogenous bases on the mRNA
What are mRNA instructions written as?
Codons
Genetic code
Shows all 64 possible codons and the amino acids they code for.
Translation
Using RNA to read the instructions on mRNA and put together the amino acids that make up the protein.
Where does translation take place?
The cytoplasm, at the ribosomes.
How many other types of RNA help the process of translation? What are they?
2, tRNA and rRNA.
What is tRNA?
Transfer RNA.
What is transfer RNA?
Folded molecules that carry a specific amino acid on one end and has an anticodon on the other.
Anticodon
Three base sequence that is complimentary to an mRNA codon.
What is rRNA?
Ribosomal RNA.
What is ribosomal RNA?
It helps make up the ribosomes.
Where does translation occur?
The ribosomes.
First step of translation
mRNA leaves nucleus, enters cytoplasm and attaches to a ribosome
What happens when mRNA attaches to a ribosome in translation?
The ribosome reads the codon on the mRNA and a tRNA molecule w the complementary anticodon arrives and binds to the codon.
What happens in translation when the tRNA w the right anticodon binds to the codon?
The tRNA then separates from the amino acid and leaves the ribosome.
What happens when the tRNA leaves the ribosome?
The ribosome moves along to the next codon and a new tRNA molecule takes its place on the mRNA strand.
What happens to the new amino acid brought in in translation?
Joins the others with a peptide bond
Polypeptide chain
chain of amino acids
What happens at the end of translation when the new amino acid binds to the others?
A polypeptide chain grows until the ribosome reaches a stop codon, and the chain lets go, folding into a protein molecule
Mutation
Change in DNA of a gene
How are mutations passed to offspring?
Thru gametes (sex cells) of affected individual
What happens when a mutation occurs in the somatic cells of an individual?
They won’t affect the offspring of that individual
Gene rearrangments
Mutations that move an entire gene to a new location
Translocation
Movement of part of a chromosome to a different location
Where can translocations happen?
Within the same chromosome or between different ones
Gene alteration
Mutation that changes a gene itself
Substitution mutation
Nucleotide w different nitrogenous base replaces original nucleotide
What may result from a substitution mutation?
Missense mutation or silent mutation
Missense mutation
Results in change in single amino acid in final polypeptide
Silent mutation
New codon codes for same amino acid; no change occurs
Insertion
Piece of DNA inserted into gene
Deletion
Segment of gene is lost
What can insertion and deletion affect?
Change the order of bases in codons, resulting in totally different codons
Frameshift mutation
A mutation such as insertion/deletion (since it causes a gene to be read in the wrong base sequence)
Evolution
Gradual change over time
Geologic evolution
Slow change of earth over 4.5 billion years
Organic evolution
Change of species over time
Evidence of evolution
Fossils
Fossils
Trace or remain of an organism that has been preserved by natural processes
What part of fossils are usually preserved?
Usually only the hard parts such as shell or bones
Where are most fossils found?
Sedimentary rock
Sedimentary rock
Forms on bottom of shallow seas + ocean
Where are the oldest layers of sedimentary rock found versus the more recent?
Oldest bottom, most recent top
Who did many fossils come from?
Extinct species.
Extinct
Species that are no longer living today. A species is said to be extinct when the last individual has died.
Evidence of evolution from living things
Anatomical similarities
Comparative anatomy
Study of structural similarities and differences among living things
What does the presence of certain types of similarity suggest?
Evolutionary relationships between species
Homologous structures
Parts of different organisms that have similar structures and development
What is homologous structures evidence of?
Some species evolved from a common ancestor
Analogous structures
Structures that have similar external forms and functions but different internal structures
Are analogous structures evidence of anything?
No.
Vestigial structures
Remnants of structures that were functional in ancestral form
Vestigial structures in modern organisms
The structures are reduced in size and serve little to no function
What are some vestigial structures in humans?
Appendix, tailbone, wisdom teeth
What can scientists do with embryological development?
Scientists can compare the embryological development of different species and determine evolutionary relationships from them
What do embryos of closely related species show?
Similar patterns of development
What does it mean if a species greatly resembles each other during development?
Closely related
What determines how alike the DNA and proteins of a species will be?
How close the evolutionary relationship is.
Main principle of Lamarck
Variations within a species weren’t constant and evolution im animals occurred based on need to adapt to changes in the environment
Year Lamarck
1809
Principles of lamarck
Law of use and disuse and inheritance of acquired characteristics
Lamarck-law of use and disuse
The more and animal uses a particular part of its body, the stronger and better developed that part gets. The less the part is used, the weaker.
Lamarck-inheritance of acquired characteristics
Characteristics that an individual develops through use and disuse could be passed onto its offspring
Who disproved Lamarck theory of acquired characteristics and how?
August Weismann, cutting the tails of mice
What do the instructions in DNA code for?
The construction of proteins.
Charles Darwin observation 1831 specimens
Observed gradual changes in species as traveled down coast South America
Charles Darwin @ Galapagos
Found many diff species of finches living there. Alike, differed slightly
Charles Darwin belief finches
Originated from mainland, evolved based on the different environments in each island.
Darwin six main points of natural selection
overproduction, competition, variation, adaptations, natural selection, speciation (OCVANS)
Darwin theory of evolution
natural selection
Overproduction
most species produce more offspring then needed to maintain population
Competition
living space/food limited, offspring compete for survival
Variation(s)
characteristics of individuals of a species may differ in certain traits
What may variations affect?
Some unimportant, others get food/escape enemies/find mates
Adaptations
Individuals w most favorable adaptations reproduce, pass traits on to offspring
Adaptation
any variation that improves individuals chance of survival
Natural selection
based on the environment, the individuals with the most favorable adaptations reproduce and pass these traits on to their offspring
Speciation
over many generations, favorable adaptations accumulate in the species and the unfavorable ones disappear. Eventually- changes are so great that the result is a new species.
Rate of evolution
Gradualism/Punctuated equilibrium
Gradualism
evolution occurs slowly and continuously over millions of years
Punctuated equilibrium
species stays same for extended periods of time, then rapid evolution in short period
How does the fossil record support Punctuated equilibrium?
Transitional fossils are missing
Biogenesis
Living things originate from other living organisms
If biogenesis is true, where did the first living things originate?
heterotroph hypothesis-natural synthesis of organic compounds led to first living things
Who formulated heterotroph hypothesis?
group of scientists 1920s and 1930s led by AI Oparin
What was it like billions of yrs ago on earth?
Atmosphere-hotter, Hydrogen, water vapor, ammonia, methane
Hydrogen
H2
Water
H2O
Ammonia
NH3
Methane
CH4
Atmosphere today
N2, O2, CO2
Who proved heterotroph hypothesis?
Stanley Miller, Harold Urey, 1953
Natural synthesis of organic compounds
Many sources of energy present-radiation, electrical energy, UV light + visible light +X rays, energy led to
Where did the energy come from in Natural synthesis of organic compounds?
Radiation from radioactive elements, electrical energy from lightning, light from sun
What did the sources of energy in Natural synthesis of organic compounds allow for?
the formation of more complex organic compounds from the simple compounds that already existed
Anaerobes
perform process called fermentation that allows to release energy, only occurs in lacking-oxygen conditions
Earliest actual cells
prokaryotic heterotrophic anaerobes
Experiment Urey and Miller
Created environment similar to early earth. boiling water in the apparatus forced the gases to circulate past sparking electrodes, creating organic compounds
Aggregates of organic compounds
Gradually organic compounds started to cluster together in groups that contained some of the characteristics of life
What were the clusters of large molecules called?
Coacervates
What were the coacervates surrounded by? What did this mean?
Shell of water molecules forming a bounding membrane, keeping the inside separate from the outside and allowing chemical reactions to occur inside
What happened when the coacervates became more complex?
They may have developed the ability to break down nutrients and release energy, allowing them to grow in size. (these were the first living things.)
Pre 1850s, most peppered moths found in wooded areas in england
pale color. darker ones rare.
Scientific name peppered moths
biston betularia
What happened to moths when England industrialized?
Heavy smoke darkened tree trunks, killed light color lichens
By 1890 what color were most moths in industrialized regions
dark
what happened w the moths
b4 industrialized revolution, light moths camouflaged in trees, giving reproductive trees advantage. then when the trees darkened, it was the dark ones who had this.
bacterial resistance to antibiotics
antibiotics usually kill bacteria, but when resistant strains appear, they multiply ands then can’t be killed
What happened when supply of organic food ran out
autotrophic cells (formed via mutation) selected for.
aerobic cells evolved due to what?
oxygen released by photosynthesis of autotrophic cells
What did the aerobic cells do once they had evolved?
Performed aerobic respiration, taking place in presence of O2 and releasing more energy then fermentation (more efficient)
What happened now that there was oxygen in the atmosphere?
Sunlight would break the double bonds of oxygen, forming ozone which protected the surface of the earth and allows organisms to move to land
Ozone
O3
What does the formation of ozone stop?
The abiotic synthesis of organic molecules
abiotic
nonliving
endosymbiotic theory
Mitochondria and chloroplasts used to be their own separate prokaryotic cells, but were taken in by others without being broken down. This was a symbiotic relationship in which both cells benefited and resulted in the eukaryotic cells.
