Exam 3 (Basic concepts) Modules 9-12 Flashcards
What is DNA?
A long molecule composed of nucleotides that contains genetic instructions and information.
What three components make up a nucleotide?
A phosphate, a sugar (deoxyribose), and a base.
What are the four nucleotides in DNA?
Adenine (A), Cytosine (C), Thymine (T), Guanine (G).
What does Adenine pair up with?
Adenine can only pair up with Thymine.
What does Cytosine pair with?
Cytosine can only pair with Guanine.
What are the four functions of DNA?
Store genetic information
Copy or replicate genetic information (to pass down future cells?
Express information
Occasionally mutate (change information)
DNA replication
The duplication of two identical replicas of DNA information
What is the job of enzymes?
The job of the enzyme is to unzip the double helix
Which strand contains the information for DNA construction?
Since both strands are complimentary, both strands contain the information.
How are errors limited?
Errors are proofread by enzymes.
What does an organisms genome determine?
Genomes determine Phenotype.
What is phenotype?
The physical characteristics of an organism.
What are genes expressed by?
Transcription and translation.
What is transcription?
Is when the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). DNA to RNA.
What is translation?
mRNA is decoded to build a protein that contains a specific amount of amino acids. RNA to protein.
What controls the expression of genes?
Chemical signals (hormones, etc)
What is DNA used for in transcription?
Template to construct an RNA molecule.
What is RNA?
RiboNucleic Acid chain composed of 4 nucleotides.
How does RNA differ from DNA?
- Includes the sugar ribose (not deoxyribose).
- Uracil (U) instead of Thymine (T)
- RNA is usually a single strand and not a double helix.
What does RNA polymerase do?
Unwinds DNA and transcribes one complimentary strand into RNA.
In RNA what does Adenine pair with?
Adenine pairs with Uracil (U).
In RNA what does Cytosine pair with?
Cytosine pairs with Guanine.
Does mRNA stay in the nucleus?
No, mRNA leaves the nucleus.
What does codon do?
Codes for one amino acid.
What structure performs translations?
Ribosomes.
What does tRNA do?
transfer RNA carries a specific amino acid to the ribosome.
Who is Gregor Mendel?
1822-1884, Augustarian monk in the Austrian Empire (Now Czech Republic).
Why were pea plants ideal?
Discrete traits (flower color, seed shape, plant height, etc), can be hand pollinated, and grow quickly.
What was the first cross Mendel did?
Yellow pea with a green pea, which resulted in the F1 generation being all yellow.
What is F1?
First filial generation produced by the parents.
What is F2?
Second filial is the offspring from F1 to interbreed.
What did Mendel deduce?
Individuals have 2 (factors) for each trait (alleles)
What is an allele?
Variant form of a gene.
What is a Punnet square?
Method to predict the outcome of offspring.
What is a dihybrid cross used for?
Look at two traits simultaneously.
What is the law of Independent assortment?
Allele pairs separate during the formation of gametes, meaning that traits are transmitted to offspring separately.
What happens to chromosomes if they are close together?
They become linked.
What is the result of incomplete dominance?
Intermediate phenotypes in heterozygotes.
When was natural selection publicly proposed?
1858
What four principles did Darwin’s concept of natural selection combine?
Overproduction (reproduction more than replacement)
competition for resources limits the size of population
differential survival and reproduction (survival of the fittest)
Inheritance and accumulation of favorable variations
What causes different fitness levels among individuals?
Interaction between environmental conditions and traits
How does fitness increase overtime?
Natural selection.
Convergent evolution
process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments
How does artificial selection differ from natural selection?
the selection occurs as a result of human choice/interaction.
What is needed for evolution to occur?
Mutation
Immigration/ gene flow
Natural selection
Genetic drift
Where do new alleles come from?
Mutation
Immigration/ gene flow
Imports alleles from other populations
What helps maintain genetic diversity?
Mutation and Immigration/ gene flow.
Mutations
the physical changes in a nucleotide sequence.
What has the potential to increase mutation rate?
Stress (mutation not a guarantee to adapt to environmental changes.
What are the reasons for mutations?
DNA sequence may be copied incorrectly during DNA replication.
Chromosomes may be “matched up” incorrectly during crossover in meiosis.
What does immigration/gene flow maintain?
Genetic diversity and genetic similarity between different populations.
What affects allele frequency in a population due to change though time?
Natural selection and genetic drift.
What does natural selection depend on?
The fitness of alleles in a particular environment, the alleles favored may differ under different circumstances.
What is selective pressure?
Can be abiotic or biotic but is the phenomena that alters the behavior or fitness of a living organism.
What does a stronger selective pressure mean?
Faster change in allele frequency,
What does it mean when an allele is at a disadvantage?
There is selective pressure against them.
What can be included in selective pressure?
Nutrient availability and herbivory.
What is competition?
The competition of resources (like water, space, light) which leads to faster growth, chemical weapons and efficient roots.
What is genetic drift?
Changes in allele, frequency that is random with respect to fitness.
Why are some alleles lost?
Genetic drift (which is not adaptive).
What happens to alleles that are more frequent due to genetic drift?
Aren’t guaranteed to increase fitness.
What is a species?
a group of individuals that may potentially interbreed in nature and defines species as groups that have low potential to reproduce with each other.
How to get a new species?
2 populations become different enough to be considered different species when they go through mutation, immigration/gene flow, natural selection and genetic drift.
Allopatric speciation
geographic isolation of populations which causes reproductive isolation and can result in the accumulation of differences large enough for population to eventually be different species.
Sympatric speciation
the evolution of a new species from an ancestral species that both continue to inhabit the same geographic region.
What could lead to allopatric speciation?
Geographic isolation.
What is the most common form of reproductive isolation?
Polyploidy which is when a cell or organism has more than two paired sets of chromosomes.
What do unusual genetic events result in?
Offspring with more than 2N Chromosomes.
What is Autopolyploid?
A polyploid organism that is formed from only one species.
What is Allopolyploid
A polyploid organism that is the product of an interspecific cross.
What is Apomixis?
A form of asexual reproduction where seeds are still produced.
What are the two types of instant reproductive isolation?
Autopolyploid and Allopolyploid.
Benefits of extra genes?
Resist and recognize diseases.
What is the central problem for organisms?
Acquiring, storing, and using carbon energy.
How are organisms classified?
On how they acquire carbon and energy.
What are autotrophs?
An organism capable of synthesizing its own food through inorganic substances using light or chemical energy.
What are photoautotrophs?
Organisms that can make their own energy using light and carbon dioxide.
What are chemoautotrophs?
An organisim (bacteria) that derives energy from the oxidation of inorganic compounds. Gain energy through chemical reactions with inorganic molecules
What are heterotrophs?
An organism that derives its nutritional requirements from complex organic substances.
Where is energy stored in biological systems?
Energy is stored as as chemical energy in the molecular bonds of organic molecules.
What are the two types of chemical reactions in metabolisms?
Anabolic and catobolic.
Anabolic reactions
Build larger molecules, and store the energy in bonds.
Catobolic reactions
Breaks down molecules into smaller ones, releasing energy.
How is energy and carbon stored during photosynthesis?
In the form of glucose.
Photosynthesis is an example of which process?
Anabolic.
Respiration is an example of which process?
Catobolic.
What important things does photosynthesis do?
Converts solar energy to chemical energy
Releases CO2
Carbon fixation: stores carbon from atmospheric CO2 in sugars that the plant (and heterotrophs) can use, and is the foundation of food chain.
What is ATP?
Adenosine triphosphate is an energy carrier for living organisms. When broken down is converted to ADP, which releases energy.
What is ADP?
Adenosine diphosphate an organic compound composed of adenosine
What organisms use respiration?
All living cells use respiration.
Why are chloroplasts green?
Contain the pigment chlorophyll a
What two steps does photosynthesis consist of?
Light dependent and light independent reactions.
Light dependent reactions
use energy from sunlight to build ATP and NADPH
Light Independent reactions
(calvin cycle) fueled by ATP and NADPH from the light reactions and fixes carbon from the atmospheric CO2 into sugars.
Where does the light dependent reactions occur?
Thykaloid membrane (chloroplast)
Where does the light independent reactions occur?
Stroma (the fluid in the chloroplast)
What happens during the light dependent reactions?
Water molecules are split apart, releasing electrons and hydrogen ions (H+), oxygen (O2) is released
What happens to the electrons that split apart?
Passed along the electron transport chain.
Electron transport chain?
generates a proton gradient that is used to drive ATP synthase.(occurs in mitochondria in eukaryotes)
How is NADPH formed?
from the NADPH+ combined with (H+) and electrons from the electron transport chain.
What is the Calvin cycle?
Uses energy from ATP and NADPH plus 3 CO2 from atmosphere to produce 3 carbon molecules.
What are the three phases of the calvin cycle?
Phase 1: Carbon fixation
Phase 2: Conversion of PGA to G3P
Phase 3: Regeration of RuBP
What does respiration start with?
Glycolysis, which occurs in the cytoplasm of the cell and is found in all cells.
Where does the citric acid cycle occur?
the mitochondria (in Eukaryotes)
What is the citric acid cycle?
A chemical reaction used by all organisms to release stored energy through oxidation. Produces 2 CO2 per acetyl CoA.
What is the final electron accepter?
Oxygen is. Then electron transport releases water.
Characteristics of Eukaryotic cells?
Nuclear envelope
2-00’s of chromosomes per cell of double strandded DNA
membrane bound organelles (plastids, mitochondria)
Have 80S ribosomes 1
asexual reproduction by mitosis
sexual reproduction by fusion
Characteristics of Prokaryotic cells?
No nuclear envelopes Have single, closed loop of double stranded DNA plus several to 40 plasmids No membrane bound organelles Have 70S ribosomes1 Asexual reproduction by fission Sexual reproduction- unknown
How are bacteria classified?
Shape (round,rod-shaped, or spiral)
Presence of a sheath around the cell wall
Surface features such as hairlike appendages
Mechanisnms of movement
Reaction of cell walls to dye.
What problems are there with classifying bacteria?
Most bacteria can’t be cultured in the lab
Not a reliable indicator of evolutionary relationships.
Who used rRNA sequences to infer evolutionary relationships?
Carl Woese (1977)
What else did Carl Woese do?
Revolutionized microbiology and phytogenetics
Indicated at least three primary lineages of life
What are the three main lineages of life?
Bacteria, Archaraea, Eukaryotes
What is Archaea closely related to?
Eukaryotes
How is Prokaryotic reproduction done?
Asexual by binary fission, 2 copies of duplicated chromsomes migrate to opposite ends of cells.
What are the three forms of gene recombination?
Conjugation, transformation, transduction
What is conjugation?
Plasmid and/or part of DNA strand is transferred from donor cell to recipient cells through pilus.
What is transformation?
Living cells acquire DNA fragments to be released by dead cells.
What is transduction?
DNA fragments carried from one cell to another by viruses
What contributes to genetic diversity?
Rapid reproduction and mutation
How do most bacteria and archaea absorb food?
Cell wall.
What are saprobic bacteria?
Digest dead, organic material (decay, etc)
What are parasitic bacteria?
Digest other living organisms (disease,etc)
What bacteria are photoautotrophic (do photosynthesis)?
Cyanobacteria
How does cyanobacteria differ from other bacteria?
Have chlorophyll a, and produce oxygen by photosynthesis. Some can even fix nitrogen.Also mutualists
What are Eukaryotes?
Plants, animals, fungi and protists.
What are protists?
All eukaryotes except plant, animals and fungi
What are the characteristics of most protists?
Mostly unicellular, but can be colonial or multicellular. Have diverse life cycles, nutrition, morphologies, and reproduction.Have no roots, stems, or leaves.
What plants are included in ‘plant like protist’?
Algae and other photosynthesizing non-plant Eukaryotes.
What are aquatic food chains based on?
Phytoplankton or photosynthesizing protists.
What are dinoflagellates?
Photosynthetic, heterotrophic, or both. Typically unicellular, contains two flagella with little to no sexual reproduction.Responsible for algae blooms and red tides.
What are diatoms closely related to?
Golden-brown algae, yellow-green algae, and brown algae.
Characteristics of golden algae?
mostly freshwater, unicellular and have flagella.
Characteristics of brown algae?
Multicellular
Sexual and asexual reproduction
Saltwater
Large and complex (can include Kelp)
Nearest relatives to land plants?
Red and green algae. Most red algae is seaweed
Where can diatoms be found?
Fresh and saltwater, on damp surfaces, most abundant in cold oceans,
Common use for diatoms?
Filtration, pest control,as abrasive
Examples of fungus-like protists?
Slime and water molds.
Examples of animal-like protists?
Heterotrophic protists that ate usually mobile.
What are plasmodial slime molds?
Many cells that have fused into a plasmodium, which is an enormous multicellular cell.
What are cellular slime molds?
Unicellular but fuse into a multicellular “slug stage” pseudoplasmodium for reproduction.
When were the first centers of agriculture began?
400-11,000 years ago.
Why people began agriculture?
Hunting was perceived as less secure
Plants are more productive
Climatic changes
Longer dry seasons
Why was artificial selection used for thousands of years?
Seed retention
Larger edible parts
Concentrated seed sets.
Who predicted famine would kill hundreds of millions of people in the 1970’s and 80’s?
Paul Ehrlich (1968)
Who is the father of the Green Revolution?
Norman Borlaug
Contributions of Norman Borlaug?
Cross varieties, screen the resulting offspring
Developed high yielding strains of wheat, rice, and other grains.
What are continued challenges?
Irrigation and fertilizers
Disease resistant varieties
Africa
Difference between changing crops/plants for a long time and genetic engineering?
Genetic engineering is a direct alteration of DNA on the molecular level, and is faster, and not restricted to close relatives or sexually reproducing organisms.
What is a transgenic organism?
An organism that a gene or genes that have been artificially inserted.
What is the name of the gene that is inserted?
Transgene (an organism that has a transgene has been transformed)
What is a genetically modified organism?
is a plant, animal, microorganism or other organism whose genetic makeup has been modified in a laboratory using genetic engineering or transgenic technology.
What is used (during the most common way of transforming plants)?
Bacterium, Agrobacterium lumefacien.
What makes genetic engineering possible?
Restruction enzymes
Advantages of CRISPR/Cas9 system over traditional gm methods?
Loosely regulated
Most common traditional methods insert randomly (CRISPR is targeted)
Waste
Expense
Screening time, no unexpected effects on other genes
More versatile and less difficult than other targeting methods
relatively inexpensive and fast
What are the concerns about altering plant genomes?
Price and availability of patented seed, economic effects , effects on agricultural methods, monocultures, susceptibility to disease genetic diversity and food lables
What commercial qualities have plants been modified to improve?
Increase yield or growth rate
Increase shelf life
Increase disease resistance
more possibilites
Using plants (algae) to help with biofuel production.
Growth rate, lipid content, and processing
What plants have been modified to create pharmaceuticals?
Tobacco plants,
What has been created using pharmaceuticals in plants?
Human proteins, human growth hormones, antibodies, vaccines for rabies, Hep B, cholera, ebola
What are the most common characteristics of transgenic crops?
Pest resistance Herbicide tolerance (glyphosphate and roundup)
What is the environment impact of BT cotton?
Lower pesticide use and toxicity
Long term effects unclear, but promising
Benefits are more dramatic in cotton than anything else
What is the the economic impact of BT cotton?
Yield increase (24%)
Profit Increase (50%)
Increase in living standards
Appears to be sustainable
What are the advantages of herbicide tolerant genetically modified crops?
Initially reduces use of more toxic herbicides
Reduces tilling and erosion
What are the disadvantages of herbicide tolerant genetically modified crops?
May increase overall herbicide use Creates superweeds (weeds resistant to herbicides)
What is transgene escape?
unintended passing of transgenes to other populations
