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Bio 101 Exam B
Test: October 21, 2011
| Question | Answer |
|---|---|
| Major quality of living things | the ability to reproduce |
| Getting two cells together | sexual reproduction, also repairing wounds, or growth from a fertilized egg |
| Basics | grow larger, divide in two |
| DNA is the key to | reproduction, development, and maintenance |
| Genome | complete collection of an organism's genetic information as linked genes in a long strand of DNA |
| Genes provide just information for the production of | Proteins |
| Proteins perform | most of the work of the cell |
| Information of Genes is found in letters | A,C,G, and T in the double helix |
| Path from DNA to protein | DNA -- RNA -- Amino Acid sequence (protein) |
| Humans have from 20,000 to 25,000genes that have all | the information to make all the proteins (especially enzymes) a cell needs |
| Each descendant of a cell, in addition to requiring nutrients, cell membrane, and organelles, must have | this information of DNA to survive |
| Simple division would mean | the new cells had half of what the old cell had |
| Duplication of both cytoplasmic and nuclear contents precedes division | so that new cells have a complete set of everything |
| Replication | Duplication of DNA |
| DNA is Packaged in | chromosomes |
| Organization of these long pieces of DNA | DNA is divided into long strands wrapped around protein (chromatin) |
| Each DNA strand is | packaged and condensed into a single chromosome |
| Replication takes one Chromosome and makes two identical copies called | sister chromatid |
| Different organisms have | different numbers of chromosomes |
| Eukaryotes have a backup of each chromosome | pairs of chromosomes are called homologus chromosomes |
| Humans have ______ total chromosomes | 46, two from each one |
| Sex chromosomes | humans and other mammals use chromosomes to distinguish between the sexes |
| Male karyotype | males have one X and one Y |
| The cell cycle keeps record of | progress of a cell over time, like a clock |
| The cell cycle is made up of a repeating pattern of | growth, genetic duplication, and division |
| Typical animal cell cycle lasts | about 24 hours |
| Two Main phases of cell cycles | interphase and mitotic phase |
| Interphase | G (gave 1) + S phase (synthesis, for replication of DNA) + G2 (Gap 2) |
| Mitosis | how the cell's newly duplicated chromosomes condense, align themselves, and separate. |
| Interphase | duplication of genetic material ends when chromosomes begin to become visible |
| Prophase | the mitotic spindle is forming, emerging from centrosomes |
| Prophase ends when the | chromatim is completely coiled into chromosomes, nucleoli and nuclear membrane disperse |
| Metaphase | the spindle is fully formed; chromosomes are aligned single file with centromeres on the metaphase plate (the plate that cuts the equator) |
| Each sister chromatid facing opposite poles | Metaphase |
| Anaphase | sister chromatids separate; each new chromosomes moves to the opposite pole |
| Telophase | is the reverse of prophase: cell elongation continues, a nuclear envelope forms around chromosomes, chromosomes uncoil, and nucleoli reappear. |
| Prophase (P for "plain to see") | chromosomes condense,nuclear envelope breaks down, spindle fibers (microtubules) are formed from the centrosomes |
| Metaphase (M for "middle") | chromosomes are aligned on the equator but pushing along the spindle with each sister chromatid facing opposite poles |
| Anaphase (A for "apart") | Sister chromatids separate; each new chromosome moves to the opposite pole |
| Telophase (T for "two nuclei") | Chromosomes de-condense, spindle breaks down, nuclear envelope forms around the two separate complements of chromosomes |
| Cytokinesis | how the cell's cytoplasm and membrane separate to create two distinct cells |
| Cytokinesis begins in anaphase | when a waistband- a contractile ring of protein filaments begins to form around the cell |
| A cleavage furrow | forms as the waistband is tightened, eventually completely pinching the cells apart |
| Plant cells- everything is similar except for cytokinesis | because plant cells have to break down and reform the cell wall |
| Pokaryotes (no nucleus) | binary fission |
| Unrestrained cell division | cancer |
| cancer is | a disease of the cell cycle |
| mechanisms that induce cell division can become hyperactive | oncogenes: stuck accelerator |
| Mechanisms that suppress cell division can fail | Tumor suppressor genes: failed brakes |
| Two types of tumors | benign and malignant |
| Benign tumors | abnormal mass of essentially normal cells |
| Malignant tumors | cancerous cells; potential to metasize through the body |
| Mitosis | "Identical" sexual reproduction: combination of desirable traits and more vanability |
| Problems with Mitosis | If combining traits were accomplished just by combining two cells, life would get incredibly complicated. Analogy to couples hyphenating their names when married. |
| N | number of different chromosomes. Adult animals have somatic cells with two sets of homologues |
| Diploid | 2n |
| Sex cells (gametes= eggs and sperm) have | one set of homologues |
| Homologues are produced by | meiosis |
| Haploid | n these cells are made only sexually reproducing organisms and only in a special organ called a gonad (testis and ovary) |
| seual life cycles involve | the alternation between a diploid phase and a haploid phase |
| The fusion of haploid gametes in the process of fertilization results in the formation of | a diploid zygote |
| Meiosis reduces | chromosome number by duplication of chromosomes (S phase) followed by two divisions instead of one (as in mitosis) |
| Mitosis(a) | "Identical" DNA is duplicated; the identical sets (sister chromatids) are divided into 2 cells |
| Results of Mitosis(a) | One diploid cell (2n) becomes two diploid cells (2n) |
| meiosis | "Reductional" each homologue is separated to reduce the total number or chromosomes from a 2n to a n. The the identical sister chromatids are separated |
| what are the two separate divisions | Meiosis I and Meiosis II |
| Results of Meiosis | one diploid cell (2n) becomes four haploid cells, 4 n |
| Meiosis begins like mitosis does | with replication of DNA is S phase of interphase |
| Meiosis I is when | homologues separate |
| Prophase I | 46 identifiable chromosomes (wach with two sister chromatids) are plain to see |
| homologues chromosomes | pair together (tetrad) and crossing over (recombination) occurs |
| Metaphase I | tetrads line up on the metaphase plate |
| Alignment of one pair bears | no relationship to any other pair (paternal chromosome on left, maternal on right) |
| Anaphase I | homologous pairs separate and move to opposite poles |
| Telephase I | at the same time, cytokinesis creates two new cells that are haploid |
| Meiosis II is when | sister chromatids separate |
| Phrophase II | 23 identifiable separate chromosomes (each still with two sister chromatids) |
| Metaphase II | Chromosomes line up at metaphase plate, this time with one sister chromatid on either side |
| Anaphase II | sister chromatids separate |
| Telophase II | two new nuclei form and cytokinesis begins to create two new cells, for a total of four haploid cells |
| What is the significance of Meiosis first problem | problem of chromosome duplication is solved, diversity is created |
| what is the significance of Meiosis second problem | Recombination |
| Recombination: | independent assortment of chromosomes makes sure that no two gametes are ever identical, number of possible combinations= 2N |
| Humans have 22 pairs of | autosomes and one pair of sex chromosomes |
| females have two | x chromosomes |
| males have one | x and one y |
| sex chromosomes pair like | homologous and separate in meiosis I, so each haploid cell that results has either an x or a y in males |
| sex is determined by the | sperm |
| spermatogenesis | spermatogonia, diploid cells that can divide by mitosis to make more of themselves, or make cells destined become sperm called primary spermatocytes |
| Primary spermatocytes complete | meiosis I to give rise to two secondary spermatocytes |
| secondary spermatocytes complete | meiosis II to make four total haploid spermatids |
| spermatids are mature in about three weeks to form | sperm, with flagella tails, concentrated mitochondria and a haploid nucleus |
| about 250 million | sperm are made eacc day, about same number in ejaculate |
| OOgonia | diploid cells that divide by mitosis early in embryogenesis, never divide after birth |
| most die before birth, but the remaining oogonia make cells destined to become | eggs, called primary oocytes |
| primary oocytes begin | meiosis I in the embryo, but do not complete it until ovulation... give rise to one secondary oocyte and a polar body |
| secondary oocytes complete | meiosis II after being fertilized by a sperm, makes one haploid egg |
| The other products of meiosis are | polar bodies |
| oocyte cytokinesis is | unequal to ensure that one large cell, 200,000 times bigger than the sperm, has enough materials to drive early divisions and feed the rapidly dividing embryonic cells |
| usually only one secondary | oocyte is released per 28-day cycle in an adult woman |
| Dizygotic | fraternal twins |
| monozygotic | identical twins |
| Humans: Meiosis creates | haploid gametes that fuse to make a diploid fertilized egg. |
| The fertilized egg divides | trillions of times by mitosis to make a baby |
| the cells in a human being continue to divide by | mitosis to grow and replace cells |
| Asexual reproduction | bacterial fission; single-celled eukaryotes; regeneration; hermaphrodites |
| Mendel worked in the period from 1856-1863, observing | generations of pea plants and applying mathematics to create a set of principles to govern inheritance |
| without ever knowing what genes were, he figured out how they | worked |
| basic units of genetics are | material elements that come in pairs |
| elements do not | change, even over many generations |
| pairs separate during the formation of | gametes |
| Life cycle allows for | rapid generations and cross and self-pollination |
| wide range of described characters, each of which had two varieties | white and purple flower color, yellow and green seed.... - called traits |
| Phenotype is | the physical function, bodily characteristic or action |
| Genotype is | the underlying genes that determine the phenotype |
| allele | alternate for of a gene (trait) |
| Monohybrid | crosses and the segregation of allele |
| starting generation of test is called | P for parental generation; took pollen from one variety and placed it on the stigma of the other variety |
| Offspring are called | F1 for first filial; could have been mix of traits, but they were all yellow (dominant) |
| To determine where green went, Mendel | self-pollinated these F1 plants |
| Nest generation of offspring is called | F2 for second filial (6,022 yello and 2,001 green) |
| Green came back, but only | as a specific proportion- 3:1 |
| Unlike his predecessors, Mendel, carefully | counted and interpreted the numbers |
| Mendel found that | varieties did not blend- one is dominant (shows up) and the other recessive (is masked by the dominant) |
| These varieties are called | alleles |
| The F3: | of the yellow F2, two-thirds gave mixtures of green and yellow (not pure yellow parents), and one-third were all yellow in the F3 (pure yellow) |
| Of the green, all were | true breeding. Alleles Y and y |
| Homozygous vs. Heterozygous | how to use a punnet squares to keep track of alleles |
| Mendel's First Law | segregation of alleles: pea cells contain two copies of each gene (alleles) |
| Alleles do not | blend (one copy, dominant, can mask the expression of the recessive copy); |
| Alleles must | separate during Meiosis (Mendel had no knowledge of chromosomes or meiosis): crosses of the F1 and F2 and F3 |
| Genotype determines | phenotype: genotpyic and phenotypic ratios |
| Law of Independent Assortment | during gamete formaiton, gene pairs assort independently due to random nature of how tetrads line up during prophase I of meiosis |
| Genes make proteins | red gene makes re pigment; with only one allele, you get only half the pigment |
| multiple alleles | phenotypes and genotypes of all possible combinations of A, B, and O |
| polygenetic inheritance | this situation creates a continuum of phenotypes |
| identical cuttings of hydrangea macrophylla can be | blue or red depending on the soil |
| take three identical Timberline plants and plant them at different altitudes | they will grow to different heights. Same genes, but environment different |
| Pleiotrophy | one gene with multiple effects. |
| How can sickle cells be both | deleterious and protective |
| Genes code for the proteins that make pigments in the eye necessary for | absorbing the different-colored wavelengths in light |
| red and green pigments are made by genes on the | x chromosome |
| mutations in the genes for these pigments result in | inability to see those colors |
| these mutations are recessive because | one good copy of the gene is sufficient for color vision affect men much more frequently than women |
| because women have two x chromosomes, | they can be heterozygous (have one mutant allele) but still have normal color vision (0.5 percent of women are color blind) |
| Men have only | one x chromosome, so if they have one mutant allele, they will be color blind (8 percent are color blind) |
| Hemophilia is cause by | a mutation in a gene that codes for a blood-clotting protein; family tree |
| sickle-cell anemia, prevalent in populations in or from | Africa |
| Red Blood cells become distorted into sickle shape in low | oxygen |
| Mutation is in the gene for the B-chain | protein of hemoglobin |
| Hemoglobin S has a substitution of | one amino acid, causing the chain to coalesce into crystals that distort the red blood cells |
| Persons with one S allele and one normal A allele do not have the condition, but are called | carriers because they can pass the gene on to their offspring (8 percent of African Americans are cariers). |
| One in 12 African-American children in the U.S. has | sickle cell anemia |
| Cystic Fibrosis | most common genetic disorder in Caucasian Americans; 1 in 25 is a carrier. Primarily affects the body's respiratory and digestive systems. It is due to a gene defect that causes the body to produce abnormally thick mucous. |
| Tay-Sachs | most common in Jewish Americans of Central European descent; 1 in 25 a carrier. |
| Babies with Tay-Sachs lack an | enzyme (protein) necessary for breaking down certain fatty substances in brain and nerve cells. These substances build up and gradually destroy brain and nerve cells, until the entire central nervous system stops working. |
| Both parents must have the allele to have a child born with | the condition |
| even in both parents are carriers, they have | one-in-four chance of having an offspring with the condition |
| In the case of sickle-cell anemia, which occurs more frequently in populations from malaria-ravaged sections of Africa, | heterozygotes are more resistant to malarial infection |
| Malaria is caused by a | protozoan parasite |
| Only one copy of the allele is sufficient for the child to | express the condition |
| Patterns of inheritance | single "faulty" allele of a gene cause damage, even with a "good" allele present |
| Confronted with medical condition running in a family, geneticists like to create family tree diagrams or pedigrees, which can be used to | determine if the disorder is dominant or recessive, and the probability of future inheritance |
| What is the relationship between DNA and proteins? | DNA encodes for proteins, and protein enzymes replicate and maintain DNA |
| Error rate minimized by | DNA polymerase proof reading |
| DNA encodes for proteins, and | protein enzymes replicate and maintain DNA |
| Mutation | permanent alteration in cell's DNA base sequence |
| Point mutations | slight change in chemical form of base, or incorrect base pairs |
| Almost all cancers begin as a mutation that is passed along at replication (somatic cells). | Mutation rate is low, but after decades of accumulated mutations, cells can become malignant |
| Heritable mutations occur in | germ-line cells (cells that divide to make sperm and eggs) |
| What is the benefit of mutations? | They create new alleles of genes |
| Polypeptides (proteins) are | large organic macromolecules made up of strands of hundreds or thousands of amino acids joined together by peptide bonds |
| There are only 20 different amino acids | they can be recombined in thousands of ways |
| How does a specific strand of amino acids always come to be strung together in the same order? | DNA (a strand of nucleotide letters, A,C,G, and T) is read as a code. Code translated into amino acids sequence. Every protein has the identical amino acids in order along its length. |
| Protein Synthesis: First Stage | DNA resides in the nucleus, but proteins are made in the cytoplasm |
| DNA is the mast set of | instructions for the cell, so it needs to stay protected and isolated in the nucleus |
| Instead of allowing DNA to leave the nucleus and travel to the cytoplasm | the cell makes a cheap copy of DNA in a smaller less permanent form |
| The process of copying DNA into RNA copy is called | transcription |
| the correct amino acid is added | at the correct time by using the information on the RNA message from the nucleus |
| Process of assembling proteins from RNA instructions is called | translation |
| the units of both RNA and DNA are composed of | sugars, phosphates and bases |
| Sugars are different in RNA and DNA | Ribose in RNA and Deoxyribose in DNA |
| RNA has nitrogen-containing bases A,G,C, and U instead of | T |
| mRNA | Messenger RNA carries instructions for sequence of amino acids in a protein |
| rRNA | ribosomal RNA is an important component of ribosomes |
| tRNA | transfer RNA is involved in matching the correct amino acid to specific instructions in mRNA |
| Just like replication | base pairing is the mechanism used to copy DNA in transcription, but here into RNA and not DNA |
| Enzyme critical to catalyzing this process is | RNA Polymerase |
| DNA is unwound and used as a template to match | complementary bases, C to G and A to U (not T) to make a new daughter strand |
| The new nucleotides are covalently linked together by the same | enzyme to make a single strand of RNA (called a transcript t) from one strand of the double helix |
| Four bases in DNA, 20 amino acids in protein | not one to one or two to one: a triplet code-three nucleotides (called a codon) signifying one amino acid |
| There are 64 different possible combinations of | the four nucleotides, more than enough for the 20 different amino acids |
| The code is | redundant (several different codons signify the same amino acid) |
| The Code carries | instruction codons for stopping and starting |
| The genetic code is | universal (same for bacteria and humans) and is good evidence for a common inheritance (evolution) |
| mRNA carries the instructions in the | codons, like a recipe |
| Ribosomes, location of | protein synthesis, are a large conglomerate of enzymes and ribosomal RNA (rRNA) in two subunits with A and P sites |
| tRNA molecules (transfer RNA) are | "translator" molecules; they can match the appropriate amino acid with the codon in the mRNA. |
| Part of the molecule binds an | amino acid, and the other end has three nucleotides (anticodon) that form a base pair with the codon in the mRNA |
| mRNA binds to the small subunit of the | ribosome |
| Start codon, AUG, brings in | initiator tRNA with the amino acid methionine, and then large subunit binds |
| tRNA that matches the next codon ferries in the appropriate | amino acid into the "A" site |
| The ribosome catalyzes the | peptide bond between the first two amino acids at the "A" site; then the ribosome jumps along the mRNA to the next codon, moving the newly formed peptide to the "P" site |
| At the stop codon, | no new tRNA comes into the "A" site, and the whole complex falls apart, releasing the new protein |
| Five amino acids are added every | second, and multiple ribosomes move along a transcript simultaneously |
| What is a gene | a segment of DNA that makes transcript |
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