Biology Review Flashcards

Question

What is it called when an injured or dying cell self-destructs by rupturing the lysosome membrane

Answer 1

* Function: * Supports the cell, maintains shape and aids in cell motility * Composed of: * _Microtubules_ * Hollow rods made of polymerized tubulin * provide support, transport during cell division, cilia and flagella * _Microfilaments_ * solid rods of actin * important for cell movement and support * _Intermediate filaments_

Answer 2

Medium is **_hypotonic_** to cell cell will **_lyse_** (burst)

Answer 3

Medium is **_Hypertonic_** to cell **_plasmolysis_** = cell will shrivel

Answer 4

Prokariotes = cell membrane Eukaryotes = mitochondria

Answer 5

DNA (Self-replication back to itself) Transcription RNA Translation Protein

Answer 6

deoxyribose (a sugar) bounded to both a phosphate group and a nitrogenous base

Answer 7

Guanine (G) and Adenine (A) Double ring

Answer 8

Cytosine (C), Uracil (U) and Thymine (T) One ring structure

Answer 9

Antiparallel arrangement A - T C - G Via hydrogen bonding

Answer 10

Unwinding and separate the two single strands and breaks the hydrogen bonds between the nitrogenous bases of eeach nucleotide

Answer 11

each new daughter helix DNA strand contains an intact strand from the parent helix and a newly synthesized strand \*\* The daughter strand of DNA formed from the parent strands are identical to the parent strands

Answer 12

3' -\> 5' synthesizing DNA 5' -\> 3'

Answer 13

64 but only 20 amino acids need to be coded

Answer 14

degeneracy or redundancy of the genetic code

Answer 15

meaning one mRNA strand codes for one polypeptide

Answer 16

* **_Transcription_** * = process through which information coded in the base sequence of DNA is used to direct the **synthesis of a strand of mRNA** * **_Steps_** 1. **RNA polymerase binds to the DNA at a promoter region**, a short DNA sequence found upstream from the site where transcription of specific RNA will take place * Humans = **TATA Box** 2. **Transcription factors** then help RNA polymerase bind to the DNA molecule and initiate transcription 3. **RNA polymerase surrounds the DNA** molecule after it has been opened by the action of DNA helicase and topoisomerase 4. RNA polymerase then recruits and **adds complementary RNA nucleotides** based on DNA sequence * **Synthesizing 5' -\> 3'** * Where RNA polymerase reads 3' -\> 5' 5. After transcription is completed, mRNA undergoes **post-transcriptional** processing * RNA that has not yet peen prcessed = **hetero-nuclear RNA (hnRNA) or pre-RNA,** and contains extra nuceotides that are not necessary to create the corresponding protein **(introns and removed by spliceosomes)** * **Guanine cap and Poly-A tail** is added to the ends of the molecule to **prevent degredation** once RNA leaves the nucleus

Answer 17

* **_Translation_** * = Process through which **mRNA codons are translated into a sequence of amino acids** * Occurs in cytoplasm and involves tRNA, ribosomes, mRNA, amino acids, enzymes and other proteins * Four steps: Initiation, elongation, translocation and termination 1. **_Initiation_** * begins when the ribosome binds to the mRNA near 5'end * Scans to find **start codon (AUG)** * Anticodon = 3'-UAC-5' 2. **_Elongation_** * **Hydrogen bonds form** between mRNA codon in the A site of the ribosome and complementary anticodon on the incoming tRNA * **Peptide bond is formed** between amino acids attached to the tRNA in A site and AA attached to tRNA in P site 3. **_Translocation_** * ribosome advances three nucleotides along mRNA in the **5' to 3' direction** and new tRNA enters 4. **_Termination_** * When one of three special mRNA trermination codons, or **stop codons (UAA, UAG, or UGA**) arrive in the A site which signal to terminate and do not code for an AA * Frequently, numerous ribosomes simultaneously translate a single mRNA molecule, forming a structure known as a **polyribosome**

Answer 18

* Ribosome: * Location of translation * Composed of two subunits, one small and one large consisting of proteins and rRNA * Make up three binding sites for tRNA: * A (aminoacyl complex), P (peptide bond form) and E site (exit)

Answer 19

The building up of new tissues from digested food materials

Answer 20

* **_Regulation_** = The control of physiological activities. The body's metabolism functions to maintain its internal environment in a changing external environment * **_Homeostasis_** = regulation by hormones and the nervous systerm * **_Irritability_** - the ability to respond to a stimulus and is part of regulation

Answer 21

* External respiration = entrance of air into the lungs and the gas exchange between the alveoli and the blood * Internal respiration = exchange of gas between the blood and the cells and the intracellular processes of respiration

Answer 22

carbohydrates and fats

Answer 23

* High energy hydrogen atoms are removed from organic molecules * = dehydrogenation and is an oxidative reaction * Subsequent acceptance of hydrogen by a hydrogen acceptor (oxygen is the final step) is a reduction component of the redox reaction

Answer 24

Degrative oxidation of glucose occurs in two stages: 1. Glycolysis = 2 pyruvate produced (energy payoff and energy production stage) 2. Cellular respiration = 34 ATP produced * TOTAL ATP PRODUCTION = 36 ATP

Answer 25

With oxygen 1. **_Glucose_** 2. **_Glycolysis_** -\> 2 pyruvate + 2 ATP + 2 NADH * **= 8 ATP (2 substrate, 6 oxidative)** * Occurs in cytoplasm 3. **_Decarboxylation of pyruvate (pyruvate processing)_** -\> 2 Acetyl - CoA + 2 NADH + 2 CO₂ * = **6 ATP (oxidative)** * Occurs from cytoplasm into mitochondria 4. **_Kreb Cycle (citric acid cycle)_** -\> 2 x (3 NADH + 1 FADH₂ + 1 ATP + 2 CO₂) * **= 2 ATP total (substrate)** * Occurs in mitochondria 5. **_Electron transport chain_** -\> 2 x (3 NADH x 3 ATP/NADH = 9 ATP and 1 FADH₂ x 2 ATP/FADH₂ = 2 ATP) + 2 ATP Total Cell Respiration * = **22 ATP****** * occurs in inner mitochondria matrix * Cytochromes = electron carriers (each carrier is reduced as it accepts e- and oxidized as e- is transfered) * O₂ is the final electron acceptor and forms H₂O 6. **_Total Aerobic catabolism process = 36 ATP_**

Answer 26

No oxygen: 1. **_Glucose_** 2. **_Glycolysis_** = 2 pyruvate + 2 ATP + 2 NADH 3. **_Fermentation_** (Pyruvate = electron acceptor) = 1. Alcohol fermentation -\> ethanol + NAD⁺ + 2 ATP 2. Lactic acid fermentation -\> lactic acid + NAD⁺ + 2 ATP

Answer 27

when glucose reacts with hexokinase to form glucose 6 phosphate (2 ATP required for step) = 2 pyruvate + 2 NADH + 2 ATP (substrate) produced

Answer 28

Fructose 1,6-biphosphate is split into two three-carbon molecules: dihydroxyacetone phosphate and glycoeraldehyde 3-phosphate (PGAL) dihydroxyacetone phosphate is then isomerized into PGAL Therefore two molecules of PGAL produced

Answer 29

When the two-carbon acetyle group from acetyl-CoA combines with oxaloacetate, a four-carbon molecule, to form the six-carbon citrate Through a series of steps, two CO2 are released and oxaloacetate is regenerated for use in another turn of the cycle

Answer 30

Disaccharides are hydrolyzed into monosaccharides, most of which can be converted into glucose or glycolytic intermediates **_Glycogen stored in the liver_** can be converted, when needed, into a glycolytic intermediate

Answer 31

* Fat moleules are stored in adipose tissue in the form of triglycerides * When needed, they are **_hydrolyzed by lipases to fatty acids and glycerol_** and are carried by the blood to other tissues for oxidation * **_Glycerol_** can be converted into PGAL, a glycolytic intermediate * A **_fatty acid_** must first be "activated" in the cytoplasm; this process requires two ATP. Once activated, the fatty acid is transported into mitochondria and taken through a series of beta-oxidation cycles that convert it into two-carbon fragments, which are then converted into acetyl-CoA. * For each round of beta oxidation, 1 NADH + 1 FADH2 is produced * **_Fats yield the greatest number of ATP / gram_** * Long term energy

Answer 32

* **The body degrades proteins only when not enough carbohydrate or fat is availabl**e * Most **_amino acids undergo a transamination reaction_** in which they lose an amino group to form an alpha-keto acid * The carbon atoms of most AA are converted into **_acetyl-CoA, pyruvate or one of the intermediates of the citric acid cycle_** * Oxidative deamination removes an ammonia molecule directly from the amino acid. Ammonia is a toxic substance in vertebrates. Fist can excrete ammonia, whereas insects and birds convert it to uric acid, and mammals convert it to urea for excretion

Answer 33

* **_Enzymes_** are proteins. * Many enzymes are conjugated proteins (proteins that consist of amino acids attached to other groups via covalent bonds) * **_Coenzyme_** * nonprotein component * can be metal cations such as Zn²⁺ or Fe²⁺ or other small organic groups and vitamins * Cofactors that bind to the enzyme by strong covalent bonds are called **prosthetic groups**

Answer 34

1. **_Lock and Key Theory_** * The spatial structure of an enzyme's active site is exactly complementary to the spatial structure of its substrate 2. **_Induced Fit Theory_** * The active site has a flexible shape that when the appropriate substrate comes in contact with the active site, the conformation of the active site changes to fit the substrate * More widely accepted theory

Answer 35

* **_Temperature:_** * As temperature increases, the rate of enzyme action **increases until an optimum temperature is reached** (usually around 40 deg C). Above that temp = deactivation * **_pH:_** * For each enzyme there is an optimum pH. Most of a **human optimum = pH 7.2 except stomach pH = 2 and pancreatic enzymes pH =8.5** * **_Concentration Enzyme and Substrate:_** * When concentrations of **both are low**, many of the active sites on enzyme are unoccupied and the reaction rate is low * **Increases in concentration of substrate** will increase the reaction rate until all of the active sites are occupied = Velocity max (V_max)

Answer 36

* **_Competitive inhibition_** * Molecules that are similar to the substrate bind to the active site of the enzyme * If concentration of both the substrate and the similar substrate are the same, they will compete for the active site * Because the active site is inhibited by the competitor the enzyme activity is inhibited * Substrate can outcompete the competitor and will **still be able to reach the V_max** * **_Noncompetitive Inhibition_** * A substance that forms strong covalent bonds with an enzume, making it unable to bind with its substrate, and consequently a noncompetitive inhibitor cannot be displaced by an addition of excess substrate * Therefore it is irreversable and **never able to reach V_max** * A noncompetitive inhibitor may be bound at, near or far from the active site * **Allosteric inhibition** = Other site than active

Answer 37

gene composed of DNA and are located on Chromosomes

Answer 38

1. Genes exist in alternative forms (allels). A gene controls a specific trait in an organism 2. An organism has two alleles for each inherited trait, one inherited from each parent 3. The two alleles segregate during meiosis, resulting in gametes that carry only one allele for any given inherited trait 4. If two alleles in an individual organism are different, only one will be fully expressed, and the other will be silent. * Expressed = dominent * Silent allele = recessive * Two copies of same allele = homozygous * two different alleles = heterozygous

Answer 39

* Test cross is an unknown crossed with a homozygous recessive (aa) * Test cross x parent AA * offspring = Aa = 100% dominant phenotype * Test cross x parent Aa * offspring = 2 Aa, 2 aa = * 50% dominant phenotype * 50% Recessive phenotype

Answer 40

Law of Independant Assortment Inheritance of one such traite is completely independant of another = dihybrid cross

Answer 41

Drosophila melanogaster = fruit fly * It reproduces often (short life cycle) * It reporduces in large numbers (large sample size) * Its chromosomes (especially in the salivary glands) are large and easily recognizable in size and shape * Its chromosomes are few (4 pairs, 2N = 8) * Mutations occur relatively frequently

Answer 42

* Incomplete Dominance = blends of the parent phenotype * ex. white and red flowers make pink * Codominance = when multiple alleles exist for a given gene and more than one of them is dominant. * Both dominant alleles are simultaneously expressed * ex. ABO blood groups as there are three different alleles: I^A, I^B and i * both I^Aand I^B are dominant and i is recessive * Does not include a blend of phenotypes...

Answer 43

* autosomes * Sex chromosomes

Answer 44

Hemophilia and color-blindness

Answer 45

* **Heredity systems exist outside the nucleus** (ex. DNA found in the mitochondria and other cytoplasmic bodies) * Important for determining characteristics of organalles * **Drug resistance** in many microorganism is regulated by cytoplasmic DNA, known as **plasmids**, that contain one or more genes. Plasmids can be massed from one bacterial cell to another via transformation

Answer 46

* Either the failure of homologous chromosomes to separate properly during meiosis I or the failure of sister chromatids to separate properly during meiosis II * **_Trisomy_** (somatic cells will have 2N+1 chromosomes) = three copies of that chromosome * **Down syndrome** = trisomy of chromosome 21 * **_Monosomy_** (somatic cells will have 2N-1 chromosome) = single copy of that chromosome

Answer 47

cosmic rays, X-rays, ultraviolet rays, and radioactivity as well as chemical compounds such as colchicine, which inhibits spindle formation = carcinogenic (cancer-causing)

Answer 48

* **_Point mutations_** = nucleic acid is replaced by another nucleic acid * **_Silent mutation_** = new codon codes for same amino acid, no change in resulting protein * **_Missense mutation_** = new codon does for a different amino acid * **_Nonsense mutation_** = new codon codes for stop codon * **_Frameshift mutation_** = addition or deletion that shifts down one that causes a complete change in the Amino Acid sequence

Answer 49

* **_Phenylketonuria (PKU)_** * molecular disease caused by the inability to produce the proper enzyme for the metabolism of phenylalanine * Individuals are unable to consume products containing aspartame * Clinical symptoms: increased concentration of phenylalanine in blood, increased concentration of phenylaline and its by-products in urine and mental retardation * **_Sickle-cell anemia_** * red blood cells become crescent-shaped because they contain defective hemoglobin

Answer 50

* **_Bacterial Genome:_** * Single circular chromosome located in the nucleoid region of the cell * Many bacteria also contain smaller circular rings of DNA called **plasmids**, containing accessory genes * **Episomes** are plasmids that are capable of integration into the bacterial genome * **_Replication:_** * Begins at a unique origin of replication and proceeds in both directions simultaneously * synthesizing 5' -\> 3'

Answer 51

* Bacteria reproduce via Binary Fission * Asexual process * Have three mechanism for increasing genetic variance of a population: 1. **_Transformation_** * foreign chromosome fragment (**plasmids) is incorporated** into the bacterial chromosome via recombination, creating new **inheritable** genetic DNA 2. **_Conjugation_** * Described like sexual mating and therefore transfers genetic material between two bacteria that are temporarily joined * Only bacteria containing plasmids, called sex factors, are capable of conjugating = F factor * **With Plasmid = F⁺ , without F^-** * Conjugation between **F⁺ and F^- = 2F⁺** * Sometimes sex factor becomes integrated into the bacterial genome and during conjugation the bridge breaks before entire transformation = **Hfr cells = high frequency of recombination** 3. **_Transduction_** * bacteriophage is a virus that infects its host bacterium by attaching to the bacterium, boring a hole through the bacterial cell wall, and injecting its viral DNA while its protein coat remains attached to the cell wall. * Transduction occurs when fragments of the bacterial chromosome become packaged into the viral progeny produced during such a viral infection * The closer two genes are to one another ona chromosome, the more likely they will be to transduce together; that fact allows geneticsts to map genes to a high degree of percision * **_Recombination:_** * Occurs when linked genes are separated, breaks and rearranges

Answer 52

* **_Gene regulation:_** * Regulation of transcription and allows them to control metabolism * based on the accessibility of RNA polymerase to genes being **transcribed and is directed by an** **operon**, which consists of structural genes, and operator region and a promoter region on the DNA before the protein coding gene * **Operator** = sequence of nontranscribable DNA = **repressor binding site** * **Promotor** = noncoding sequence of DNA that surves as the **initial binding site for RNA polymerase** * regulator gene, which codes for the synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase * **_Inducible systems_** * Require the presence of a substance, **inducer**, for transcription to occur * **repressor binds to operator = no transcription (bound to operator)** * **inducer bind to repressor = transcription** * Inducer-repressor complex formed and cannot bind to operator to inhibit transcription * **_Repressible systems_** * are in a constant state of transcription unless a corepressor is present to inhibit transcription * **repressor + corepressor = no transcription (bound to operator)** * corepressors are often end products of biosythetic pathways they control * **repressor only = transcription**

Answer 53

* Lamarckian = use or disuce and acquired characteristics * ex. Long necks of giraffs? * Darwin = fitness to survive and reproduce

Answer 54

1. Overpopulation: * more offspring are produced than can survive 2. Variations: * Offspring naturally showed variation/differences in their characteristics compared to those of their parents. beneficial mutations 3. Competiton: * compete for necessities of life 4. Natural selection: * some organisms have variations that give them advantages over other members of the species 5. Inheritance of the variations: * individuals that survive live to adulthood to reporduce and thus transmit these favorable variations 6. evolution of new species: * over generations of natural selection, the favorable changes (adaptations) are perpetuated in the species

Answer 55

* Speciation: * is the evolution of new species, which are groups of individuals that can interbreed freely with each other but not with members of other species * Demes * before speciation, small, local populations form within a species * if these demes become isolated, speciation may occur

Answer 56

* Biologists seek to understand the evolutionary relationships among species alive today, evolutionary history = phylogeny * branches: 1. **_Convergent evolution_**: groups develop in similar ways when exposed to similar environments 2. **_Parallel evolution_**: similar to convergent evolutionbut occurs when a more recent ancestor can be identified 3. **_Divergent evolution_**: occurs when species with a shared ancestor develop differing traits due to dissimilarities between their environments

Answer 57

* The population is very large * No mutations affect the gene pool * Mating between individuals in the population is random * There is no net migration of individuals into or out of the population * The genes in the population are all equally successful at reproducing

Answer 58

p + q = 1 (p + q)² = 1² p² + 2pq + q² = 1 where: p = frequency of dominant q = requency of recessive

Answer 59

* **_Fossil Record: Direct evidence_** * Types of fossils: teeth, bones, in rocks, tar pits, ice and amber (fossil resin of trees), Petrification = minerals replace the cells of organisms, imprints, molds and casts * **_Comparative Anatomy:_** * Homologous Structures: structures that have the same basic anatomical features and evolutionary origins * Analogous Structures: structures with similar functions but may have different evolutionary origins and entirely different patters of development * **_Comparative Embryology:_** * Stages of development of the embryo resemble the stages in an organism's evolutionary history * two-layer gastrula = similar to hydra, a cnidarian * Three-layer gastrula = similar to flatworm * The earlier the stage at which it diverges, more dissimilar * **_Comparative Biochemistry (physiology):_** * Most organisms demonstrate the same basic needs and metabolic processes, require nutrients, similar organelles and ATP energy * **_Vestigial Structures:_** * Have no known current function but apparently had some ancestral function

Answer 60

* First forms of life lacked the ability to synthesize their own nutrients = **heterotrophs** * depended upon outside sources of food * Primitive seas containsed simple inorganic and organic compounds such as: * salts, methane, ammonia, hydrogen and water * energy = heat, electrocity, solar radiation (X-rays and UV), cosmic rays and radioactivity

Answer 61

* The presence of building blocks (salts, methane, ammonia, hydrogen, water and energy) may have led to the synthesis of simple organic molecules * sugars, amino acids, purines and pyrimidines. these molecules dissolved in the "primordial soup" * after many years, the simple monomeric molecules combined to form a supply of macromolecules * Evidence of organic synthesis: * An aparatus was set up with the primordial soup ingredients on early eart to see if macromolecules could develope and they did * Formation of primative cells: * Colloidal protein molecules tend to clump together to form coacervate droplets. * droplets tend to posses a definite internal structure and highly likely that they developed on early earth

Answer 62

* The primitive heterotrphs slowoly evolved complex biochemical pathwyas, enabling them to use a wider variety of nutrients * Evolved anaerobic respiration processes to convert nutrients to energy however, needed nutrients faster than the environment could provide * Autotrophs are able to produce organic compounds, including energy-containing molecules, from substances in their surroundings

Answer 63

* **_Autotrophic anaerobes_** = chemosynthetic bacteria * **_Autotrophic aerobes_** = green plants and photoplankton * **_Heterotrophic anaerobes_** = yeast * **_Heterotrophic aerobes_** = amoebas, earthworms and humans

Answer 64

similar in origin but not necessarily in function

Answer 65

convergent

Answer 66

The percentage of the population with blue eyes (genotype = bb) = 36% = q² = 0.36; therefore q = 0.6 because p + q = 1 , p = 0.4 the frequency of heterozygous brown eyes is 2 p q = 2 (0.4) (0.6) = 0.48 = 48% is heterozygous for brown eyes

Biology Review Flashcards

(93 cards)