2pt q's Flashcards
What is homeostasis. Give an example.
Homeostasis is the ability to sense and react to stimuli in order to maintain a constant internal environment when the external environment changes. Ex: Dilation of capillaries to release heat in response to high temps in the environment.
Describe the flow of energy and cycling of materials through the ecosystem
Producers make their own food by extracting energy and nutrients from non-living sources (sun/water/co2). Consumers obtain energy and nutrients by eating other organisms. Decomposers obtain energy and nutrients from wastes or dead organisms and recycle
List the two parts of the scientific name and define them
Genus/Species Genus is a group of species that share unique features. Species is a distinct type of organism that share one or more heritable traits and can interbreed with each other.
List the factors that contribute to water’s life giving properties
Water is cohesive and adhesive, it regulates temperature, expands when frozen, participates in chemical processes, and it is a solvent.
How is a peptide bond formed?
A peptide bond is formed by the dehydration synthesis of amino acid monomers. (bonds between carboxal and hydroxal groups)
State the cell theory 3/3
Early: Organisms made of one or more cells, Cell is the fundamental unit of life, Cells come from preexisting cells. Additional: All cells have same basic chemical composition, All cells use energy, All cells contain DNA that is duplicated and passed on as the cell divides
What is the difference between a nucleus and nucleoid?
A nucleoid is an irregularly shaped region of the cytoplasm that contains a single, circular DNA (found in prokaryotic cells). A nucleus is a membrane bound sac that houses DNA, found in eukaryotic cells.
Define endergonic and exergonic reactions
An endergonic reaction results in a net gain of energy - the reactants have less potential energy than the product. An exergonic reaction results in a net loss of energy - the product has less potential energy than the reactants.
Define oxidation reduction reactions
Redox reactions link an exergonic process with and endergonic one. An electron donor would undergo an oxidation reaction, losing energy because this is an exergonic reaction. The molecule simultaneously gaining this electron would be reduced in an endergonic reaction. The electron transferring reactions play a vital role in photosynthesis and cellular resp.
Define passive transport and list the three different kinds of passive transport
Transport by which ions or molecules move along a concentration gradient (from high concentration to low concentration/does not require energy). Simple diffusion, facilitated diffusion, osmosis (water moves down its own gradient.)
What are enzymes? List the factors that contribute to the enzyme substrate specificity?
Biological catalysts that increase the rate of chemical reactions. They are not consumed in the process, and they lower the activation energy. Complementary shape, charge, and hydrophobic/hydrophilic factors contribute to enzyme specificity.
Define aerobic cellular respiration and write the chemical equation
C6-H12-O6 + (6)O2 ——–> (6)CO2 + (6)H2O + 36ATP A form of cellular respiration that requires oxygen in order to break down organic molecules for the production of ATP.
List and define 2 methods by which ATP is made in the cell
Substrate level phosphorylation - An enzyme directly transfers a phosphate from a high energy donor to an ADP creating ATP (i.e. glycolysis). Chemiosmotic phosphorylation uses ATP synthase and the potential energy of a proton gradient to make ATP. As the gradient dissipates ATP synthase harnesses the energy into a usable form. (ATP)
State where chlorophyll is located in a chloroplast and the function of chlorophyll in photosynthesis
Chlorophyll is located in photosystems embedded in thylakoid membranes. Hundreds of chlorophyll are found in antennae pigments which surround 2 modified chlorophyll in the reaction center. Antennae pigments gather light energy and pass it to the reaction center where it is transferred to electrons.
What is water’s role in light reactions?
Electrons are replaced in photosystem II by hydrolysis. A molecule of water is split into 1/2 O2, 2H+ and 2 electrons. The 1/2 O2 is doubled and either released to the environment or used in respiration. The H+ remains in the thylakoid space.
Briefly describe how C4 and CAM plants differ in carbon fixation reactions.
In the C4 pathway, CO2 combines with 3C molecule to form 4C oxaloacetate which is usually reduced to a malate. Malate moves into adjacent bundle sheath cells where the CB cycle fixes the carbon a second time. Crassualacean acid metabolism uses temporal separation. Stomata open at night, mesophyll cells incorporate CO2 into malate and store it in vacuoles. During the day, malate is moved into chloroplasts, release CO and it is fixed in CB cycle.
What is glysolysis/Where does glycolysis happen in the cell/What is the net yeild of ATP and NADH at the end of glycolysis
Glycolysis is a universal reaction that splits glucose into (2) 3C pyruvate. Glycolysis requires energy to start and yeilds a net of 2 ATP and 2 NADH. Glycolysis occurs in the cytoplasm.
Describe the differences between lactic acid fermentation and ethanol fermentation
Ethanol fermentation produces CO2 and requires an intermediate (pyruvate–>aceltylaldehyde–>ethanol). Lactic acid fermentation does not produce CO2 and does not use an intermediate (pyruvate–>lactate).
List the three stages of aerobic cellular respiration and where in the cell the stages occur
Glycolysis/Kreb’s cycle/Electron transfer phosphorylation cytoplasm/mitochondrial matrix/inner membrane of mitochondria
Define photorespiration
The process by which in the presence of light plant consumes oxygen and releases carbon dioxide (instead of fixing carbon dioxide) during photosynthesis.
List the two stages of photosynthesis and state where in the chloroplast of the plant cell does each stage occur?
Light dependent reactions happen in the thylakoid membranes. Light independent reactions happen in the stroma.
What are the 3 types of RNA and how does each contribute to protein synthesis?
mRNA carries the genetic code information from DNA. tRNA is a “connector” that connects the information in mRNA to an amino acid. rRNA is the main component of ribosomes that assembles the polypeptides and also catalyzes bonds.
Describe the functional differences in RNA and DNA
DNA: stores RNA and protein encoding information, transfers information to next generation of cells. RNA: carries protein-encoding information, acts as a connector to amino acids, helps to make proteins, catalyzes some reactions.
Describe the structural differences in RNA and DNA
Single vs. double strand, Uracil instead of Thymine, Ribose vs. Deoxyribose, RNA smaller than DNA.
State Chargaff’s rule
- The amounts of thymine and adenine in DNA are the same and the amounts of cytosine and guanin are the same (A=T, G=C). 2. The proportion of adenine and guanine differs among species.
Where are anticodons and codons located? List the start and stop codons. Which amino does the start codon code for.
Codons are located in mRNA, anticodons in tRNA. AUG - methionine, UAA, UAG, UGA
How is mRNA modified after transcription? (post transcriptional modification)
mRNA is modified before leaving the nucleus. On the 5’ end a modified guanine cap is added which helps ribosomes attach. On the 3’ end adenines are added forming a poly A tail which determines the longevity of the mRNA. Introns are removed and exons spliced together.
State the function of mitosis in multicelled eukaryotes and in single celled organisms
In single celled organisms, mitosis is the basis for asexual reproduction. In multicelled organisms mitosis is used for growth and development and to repair and replace damaged tissue.
What are the 4 major checkpoints in the eukaryotic cell cycle?
G1 - checks for damaged DNA, S - Checks that DNA is replicating properly, G2 - checks if all the DNA has replicated and that spindle machinery is in place, Metaphase - checks if the chromosomes are aligned properly and if the spindle fibers are connected to chromosomes properly (at kinetochores).
Compare sexual reproduction and asexual reproduction
Asexual: Form of reproduction in which offspring arise from only one parent, by mitosis. Sexual: The combination of genetic material from 2 individuals to create a third. Meiosis/haploid/fertilization/diploid
Compare haploid and diploid cells
Diploid cells have 2 sets of chromosomes, one from each parent and are noted as 2n. Haploid cells have 1 set of chromosomes and are noted as n. Fertilization and mitosis create diploid cells, meiosis creates haploid cells.
Explain Aneuploidy/Polyploidy
Aneuploidy is any deviation from the exact multiple of the haploid number of chromosomes. Most aneuploids arise by nondisjunction and chromosomes may be present in multiple copies (trisomy) or one of a homolous pair may be missing (monosomy). Polyploidy is an organism or cell having more than twice the haploid number of chromosomes and is the result of total nondisjunction during mitosis or meiosis.
Define genotype and phenotype
A genotype is the combination of alleles for a particular gene. A phenotype is an observable characteristic of an organism.
Mendel’s law of segregation and Law of independent assortment
Segregation: The two alleles of each gene are packaged into separate gametes; they segregate from each other during gamete formation. Ind Asst.: The segregation of the alleles for one gene does not influence the alleles for another gene. Alleles for 2 different gene are randomly packed in respect to each other.
P, F1 and F2 generations
P is the parental or starting generation. F1 and F2 (filial) indicate the generation of offspring (1st and 2nd respectively)
What is a test cross?
A test cross is a mating of an individual of an unknown genotype for a trait with an individual that is homozygous recessive for that same trait. The phenotypic ration of the offspring can be used to determine the genotype of the unknown individual.
Explain epistasis and Pleiotropy
Epistasis: One gene masksor affects another gene’s expression (i.e. baldness hides the effects of a widow’s peak) Pleiotropy: One gene has multiple effects on the phenotype. (i.e. one protein is used in many parts of the body. Marfan)
How are dideoxynucleotides different from regular nucleotides
Dideoxynucleotides are lacking a 3’ hydroxal group found in deoxynucleotides. Thus, they can’t form a 3’-5’ phosphodiester bond required in chain elongation and the sequence is teminated when a dideoxynucleotide is encountered. They are also fluorescently tagged.
Define restriction enzymes with one example
An enzyme having the property of cleaving DNA molecules at or near a specific sequence of bases. Used for gene splicing, example: Eco RI
Define an STR and how is it used in DNA profiling
A short tandem repeat is 2-5 nucleotides long, they repeat one after another, can be up to 50 repeats long, and are found in non-coding regions of DNA. Individuals have different numbers of these repeats so they can be used as a unique identifier. DNA is amplified w/ PCR and 13 repeats are marked with fluorescent tags. Electrophoresis and fluorescent imaging are used to create a unique profile. (court cases, forensics)
Compare and contrast stem cells and differentiated cells/list define the 2 categories of animal stem cells
Stem cells are undifferentiated and can specialize to become any type of body cell. Differentiation is the process by which less specialized cells become more specialized. Differentiated cells are cells that have specialized to have a specific function. Embyonic/totipotent/embryos/all types
Adult/pluripotent/various parts/limited subset
Define microevolution and macroevolution
Small scale evolution - realatively short term changes in the allele frequency from generation to generation. Large scale evolutionary change - the descent of different species from a common ancestor over many generations/long periods of time.
State the theory of evolution by natural selection
All species present on Earth today are descendants of a single common ancestor, and all species represent the product of millions of years of accumulated micro evolutionary changes.
Define natural selection
Natural selection is the differential survival and reproduction of individuals of a population that vary in the details of their shared, inherited traits.
Briefly explain the mechanisms of evolution
Genetic drift - Change in allele frequencies that occurs purely by chance (stepped on beetles) Migration - A group of a species joins another group increasing the frequency of the alleles that it carries in the population. Mutation - Change in a DNA seq Natural Selection - differential survival and reproduction of ind of a pop that vary in the details of their shared inherited traits.
Describe the endomembrane system. (4)
The endomembrane system is a series of interacting organelles between the nucleus and cell membrane of a eukaryotic cell that exchanges materials in transport vesicles. It makes/modifies/transports proteins and lipids for secretion or insertion into the cell membrane. It also destroys toxins and recycles wastes. It includes: nuclear envelope, ER, GA, lysosomes, vacuoles and cell membrane.
What contributes to genetic variability?
In crossing over, homologous chromosomes align and swap segments with each other which results on the chromosomes having new allele combinations. Crossing over occurs at random, so the gametes produced in one round of meiosis are not identical in the subsequent round. In independent assortment, homologous chromosomes can be attached to either spindle pole in metaphase 1, so each homologue can be packaged into either one of two nuclei. In fertilization, chance combinations of maternal and paternal chromosomes combine to produce a unique combination of genetic information.
Describe the cell cycle
The cell cycle consists of three phases that occur from the point of the cell’s emergence until the cell divides into daughter cells. During interphase, the cell is not dividing, but protein synthesis, DNA replication, and other basic functions are occurring. Following interphase is mitosis during which the replicated genetic material divides. Finally, in cytokinesis, the cytoplasm divides and the cell separates. After cytokinesis, the daughter cells enter interphase and the cell cycle begins again.
Ionic bond
An ionic bond is an attraction between oppositely charged ions. It is a strong bond, but broken easily. (NaCl)
Covalent bond
A covalent bond is a strong, chemical bond in which two atoms share electrons. Depending on the electronegativity of the atoms, the bond will be polar or nonpolar covalent. (H2O)
Hydrogen bond
A hydrogen bond is a weak attraction between a highly electronegative atom and a hydrogen atom participating in a separate polar covalent bond. It is not a chemical bond, and is easily broken. (Water to water)
What is ER, two types
ER is an extension of the nuclear envelope that is folded into 2 types of membranes - smooth and rough. Rough ER is studded with ribosomes and functions in protein synthesis. Pro folded into tertiary form here. Smooth ERnis lacking ribosomes and synthesizes lipids, removes toxins and recycles wastes.
3 types of respiration
The 3 types of respiration are anaerobic, aerobic and fermentation. Aerobic respiration is the complete oxidation of glucose to CO2 in the presence of oxygen (glycolysis-krebs-electron transport phosphorylation) producing 36-38 ATP. Anaerobic respiration is essentially the same as aerobic respiration, except the final electron acceptor is not oxygen and the byproduct not CO2. It produces 18 ATP. In fermentation, electrons from NADH reduce pyruvate and regenerate NAD+. Lactic acid and alcholic fermentation produce 2 ATP.
Protein structure
Peptide chains fold into unique, 3D forms depending on the order and kinds of amino acids. The primary structure is a polypeptide chain with bonded carboxyl and hydroxal groups. The secondary structure forms coils, loops and sheets as the result of hydrogen bonds between parts of the polypeptide. The tertiary structure gives the polypeptide its overall shape (from H, ionic and covalent bonds forming.) The quarternary structure is the shape arising from interactions between multiple polypeptide units.
Transcription
In the Initiation phase, enzymes unzip the DNA double helix exposing the template strand. RNA polymerase then attaches to a promoter (a DNA sequence that signals the gene’s start.) In elongation, RNA polymerase moves over the gene in a 3’ to 5’ direction, unwinds the DNA helix, reads the base sequence, and joins free RNA nucleotides into a complementary strand of mRNA. In termination, a terminator sequence signals the end of the gene, and the RNA, DNA and RNA polymerase separate. DNA becomes a double helix again. A RNA copy of a gene has been produced.
Krebs
In Acetyl CoA formation, 2 pyruvate are broken down into 2 Acetyl CoA, 2 CO2 and 2 NADH. Acetyl CoA enters the krebs cycle and is added to oxaloacetate to form citrate. Several intermediates rearrange and oxidize citrate eventually turning it back into oxaloacetate and produce 2 ATP, 4 CO2, 2 FADH2, and 6 NADH. CO2 is released from the cell, and NADH and FADH2 are passed to the electron transport chain. The second stage takes place in the mitochondria matrix.
LIDR
Carbon/light independent reactions take place in the stroma and synthesize CO2 into organic molecules. Catalyzed by ribulose biphosphate carboxylase/oxygenase (rubisco), 2 CO2 are added to 2 ribulose biphosphate (RuBP) to form an unstable intermediate. The intermediate splits into (12) 3C phosphoglycerate (PGA). Using the electrons and H+ from NADPH (12 NADPH–>12 NADH), PGA is transformed into (12) 3C phosphoglyceraldehyde (PGAL). 2 PGAL are used to make one glucose. 10 PGAL are used in RuBP regeneration - powered by ATP (6 ATP –> 6 ADP), PGAL is rearranged into 5 RuBP. RuBP can then be re-used.
LDR
PSII - pigments collect and trans energy. Electrons are replaced by. ETCI pumps in H+. Gradient creates ATP. PSI repleneshes E. ETCII reduces NADP+ to NADPH to stroma.
