Biology Midterm Study Guide
Biology Midterm Study Guide Biol 1010k
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This 21 page Study Guide was uploaded by Amber Notetaker on Tuesday September 27, 2016. The Study Guide belongs to Biol 1010k at Georgia Highlands College taught by Dr. Tom Harnden in Fall 2016. Since its upload, it has received 64 views. For similar materials see Introduction to Biology in Science at Georgia Highlands College.
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Date Created: 09/27/16
DNA Important people Friedrich Miescher o 1869 o Removed nuclei from pus cells o Isolated the material from the nucleus > Nuclein: rich in phosphorus, but lacked sulfur Significance:Proteins were thought to be genetic material because they had 20 different amino acids that produced diversity…but were high in sulfur - Analyzed nuclein > contained nucleic acid DNA: Deoxyribonucleic Acid RNA: Ribonucleic Acid Frederick Griffith o 1931 o Experimented with bacterial organism that caused pneumonia in mammals S= Smooth; resistant Injected mice with two strains of pneumococcus - Encapsulated, Virulent (S) Strain to mice immune system - Non-encapsulated, Non-Virulent (R) strain - They lived R=Rough; not Next, he injected the mice with a heat-killed (S) strain to determine if the capsule resistant > will be alone was responsible for the virulence of the (S) strain destroyed by - The mice lived immune system - So, the heat-killed (S) strain had been rendered ineffective Lastly, he injected the mice with both a heat-killed (S) strain, and a live (R) strain - The mice died - The living (S) strains were isolated from the bodies - Griffith’s Conclusions: There must have been a substance that was able to synthesize the capsule, and this substance transformed the dead (S) strain to the living (R) strain > which results in a Transformed (R) strain Oswald Avery o W hat is the transforming substance??? o It’s DNA Protease, RNAse, and DNAse are all enzymes Evidence: - Protease can’t prevent transformation - RNAse can’t prevent transformation - DNAse DO prevent transformation Bacteriophage: A virus that infects bacteria; composed of DNA and protein Hershey and Chase o 1952 o Demonstrated the DNA was genetic material, not proteins by using Bacteriophage o They wanted to determine if the capsule (protein) or the nucleic acid (DNA) entered the bacteria, and controlled the reproduction of the virus 35 32 Protein (capsule) was labeled ???? while DNA (nucleic acid) was labeled ???? - Protein capsule was not injected into bacterial cell > no change in bacteria’s activity - The nucleic acid (DNA) WAS injected into bacterial cell > redirected bacteria’s activity - This reinforced that DNA was genetic material - Erwin Chargaff o 1940’s o Used new chemical techniques to analyze the base content of DNA A: Adenine T: Thymine Results of analysis C: Cytosine - The amount of the bases varied from species to species Chargaff’s Rules! G: Guanine - In every species > A=T and C=G - Variability is staggering - Total number of nucleotide sequences : 4140,000,000 Rosalind Franklin o Produced X-ray photo of crystalized DNA o Proved that DNA is a helix, and at least one part of the helix is repeated James Watson and Francis Crick o 1962 > won Nobel prize for DNA model DNA Model - Double Helix - Sugar phosphate molecule ‘backbone’ - Paired nitrogen bases - Complimentary base pairing - Their model matched Chargaff’s rules and Franklin’s photo Meselson and Stahl o Showed Semi-conservative DNA replication by using Nitrogen isotopes > ???? 14 and 15 ???? Semi-Conservative DNA Replication During replication, the two strands of DNA separate. Each strand acts as a template for the new strand; the copy. Sir Archibald Garrod o Suggested link between genes and proteins Inborn Error of Metabolism o Coined the phrase inborn error of metabolism Rare genetic (inherited) disorders in which the body cannot properly turn food into energy Beadle and Tatum o Formulated one gene – one enzyme hypothesis o One gene specifies synthesis of one enzyme Pauling and Itano o Formulated one gene – one polypeptide hypothesis o Each gene codes for one polypeptide of a protein Nierenberg and Matthei o Discovered that the codon UUU codes for phenylalanine How to remember purines vs pyrimidines Genetic Material Cytosine, Uracil, and Thymine are Stores info that controls development of cells Pyrimidines, because you CUT a pie Is stable so it can replicate (PY) Undergoes mutations for evolution A pie is in the shape of a circle. Provides genetic variability A circle is one ring. DNA Structure Guanine and Adenine are Purines DNA contains four nucleotides Green Apples are Pure o Purines: single ring - Adenine GuaNiNe and AdeNiNe each have - Guanine two ‘N’s in their names o Pyrimidines: double-ring - Thymine Two ‘N’s = Two rings - Cytosine - **Uracil is also a pyrimidine** How to remember the base pairings Complimentary Base Pairings Adenine and Thymine o A = T A and T are straight lines o C = G Cytosine and Guanine C and G are curved lines Hydrogen Bonds o A is hydrogen bonded to T with 2 bonds How many H bonds between C and o C is hydrogen bonded to G with 3 bonds G? 3 H-bonds Because C is the third letter of the alphabet DNA Replication Takes place during the S phase of the cell cycle Single-stranded chromosome becomes double-stranded Identical chromosome copy DNA double helix is unwound by helicase, and the weak hydrogen bonds are “unzipped” by the helicase DNA Polymerase begins the binding of the complimentary bases The pairings come from free nucleotides in the nucleus Bases are added in the 5’ to 3’ direction Remember: A = T and C = G Helicase and DNA polymerase are enzymes. The bases are added to the leading strand without stopping. Leading strand is continuous On the lagging strand, the bases are Lagging strand is discontinuous added in Okazaki fragments because the pairings are going in the opposite direction 3’ 5’ 3’ 5’ Lagging Leading Okazaki fragments are sealed back together by DNA ligase Results Two identical daughter strands DNA replication is different in prokaryotic and eukaryotic cells Eukaryotic Prokaryotic Linear chromosome structure Circular chromosome structure Telomerase is present No telomerase Multiple points of origin Single point of origin Replication rate is: 50 to 100 Replication rate is : 1000 Possible Replication 6 nucleotides, or 500-5,000 nucleotides, or 10 base pairs base pairs per minute Errors per minute Takes hours to complete DNA Genetic Takes 40 minutes to complete replication DNA replication Mutations Eukaryotic replication spreads with - Inversions - Deletions replication bubbles: places where DNA strands are separating and - Duplication replication is occurring. s Replication forks are the V-shaped ends of the replication bubbles DNA vs RNA DNA RNA Contains deoxyribose sugar Ribose sugar Bases: adenine, cytosine, Bases: adenine, cytosine, guanine, and thymine guanine, and uracil Double-strand Single-strand Confined to nucleus Not confined to nucleus Modification only occurs if Undergoes significant there is a mutation modification Transcription DNA to RNA A portion of the DNA is copied to mRNA by RNA polymerase Occurs in nucleus In eukaryotic cells 1. DNA unwinds (again, b/c of weak hydrogen bonds) and unzips (again) by an RNA polymerase attaching to a promoter 2. As RNA polymerase moves along, RNA nucleotides bind to DNA nucleotides 3. This keeps occurring until you have the mRNA that needs to be translated outside the nucleus 4. The new RNA strand hangs to the side while the DNA strands join back together > this hanging piece is now mRNA 5. Terminator Sequence: RNA polymerase stops; mRNA transcript is released 6. Spliceosomes remove introns, and exons rejoin > this is the modified mRNA that can be correctly read. Intron: non-coding segments of DNA Exon: segments of DNA that will eventually be expressed as a polypeptide Ribosomal RNA (rRNA): combines with already constructed proteins to form Translation the ribosomes where polypeptides are synthesized mRNA strand to polypeptides Messenger RNA (mRNA): takes occurs in cytoplasm the coded message of a DNA the mRNA transcript from transcription is carrying the DNA code strand out to the cytoplasm and ribosomes for constructing the polypeptides 1. mRNA travels to ribosome 2. Ribosome “reads” the codons Transfer RNA (tRNA) transfers specific amino acids to the 3. the start codon AUG initiates translation ribosome for addition to the 4. tRNA brings the anti-codon (amino-acid) to match with the codon building of the polypeptide 5. the first tRNA (with a match to AUG: UAC) enters the ‘P’ site chain 6. Second tRNA comes through ‘A’ site 7. The second amino acid connects to the first amino acid, and so on 8. Each time a new tRNA comes into the ribosome, the amino acid that it was carrying gets added to the elongating polypeptide chain. 9. A stop codon stops the process > polypeptide chain is complete Think… P site: where the Polypeptide chain is A site: where the Amino Acids enter There’s also an ‘E’ site E site: where the tRNA Exits APE This is the direction the tRNA move First tRNA enters A First tRNA moves next door to P while second tRNA enters A Then when third tRNA is ready to enter A, they shift again First tRNA moves to E, and second tRNA moves to P, and third tRNA enters A The Genetic Code A triple code comprised of 64 three-base code words, or codons The code is degenerate Third base can change without getting a different amino acid > wobble base Wobble base allows for mutations to occur without changing the polypeptide Genetic code is unambiguous=each triplet only has one meaning genetic code is universal=each triplet codes for the same amino acid in every organism Genetic Mutations permanent change in DNA sequence Point mutation: change in single nucleotide > change in specific codon - Abnormal polypeptide shape occurs because of a point mutation occurring anywhere other than the wobble base, resulting in a shorter protein or wrong amino acid added to the strand - Example: sickle cell anemia Frameshift mutation: shift in reading frame - THE CAT ATE THE RAT > C is deleted > reading frame shifts by one base > THE ATA TET HER AT - result of a deletion or insertion of a nucleotide - results in new codon sequence and nonfunctional protein - Examples: PKU, Cystic fibrosis, and Androgen, and insensitivity Phenotype = Physical Genetics Homo: same Genotype: Combination of alleles Hetero: different Phenotype: Physical expression of alleles Poly: Many Homozygous dominant: Two dominant alleles (AA) Homozygous recessive: Two recessive alleles (aa) Marfan Syndrome Heterozygous: One dominant allele and one recessive allele (Aa) Effects the connective tissues P: parental generation Abnormalities: skeletal, heart, F1: first generation offspring blood vessel, lung, stretch marks, eye F2: second generation offspring Pleiotropy: Phenotypic expression of the alleles at a single location on chromosome effecting two or more traits > Marfan syndrome Polygenic Inheritance: Single trait controlled by more than two genes; aka multifactorial inheritance > skin color (4-6 genes) Continuous variation: Many human traits display a range of small differences in most traits > eye color Nondisjunction: the failure of homologous chromosomes to separate during meiosis I, or chromatids during meiosis II Mendel’s Findings Gregor Mendel Each organism Crossed pea plants contains two noticed pattern of inheritance traits alleles for each trait true-breed plants self-pollinated > identical offspring hybrids: Offspring with different traits The alleles separate during the formation of gametes, so each gamete contains only one allele for each trait Law of independent assortment: Allele pairs separate independently during the formation of gametes > traits are transmitted to offspring independently of one another. Dominant-recessive inheritance: hitchhiker thumb rolling the tongue hairline PTC tasting Dominant overpowers recessive Male and Female Incomplete Dominant Inheritance Equal chance of getting gene: Traits are not masked in the heterozygous form Intermediate phenotype is produced Dominant-recessive Red flowers + White flowers = Pink flowers inheritance: Incomplete Dominant Sickle-cell anemia Inheritance Codominant Inheritance Genes are carried on Codominant Inheritance and Multiple Alleles autosomal chromosome demonstrate more than two alleles Unequal chance of getting gene; Two dominant alleles > can’t overpower each other Sex-linked Mixture of two alleles shows in phenotype Genes are carried on sex Red flower + White flower = Red flower with white dots chromosome Blood type Sex-Linked Most traits carried on X chromosome Melanin Deposition Epistasis the interaction of genes that are not alleles EE or Ee promotes deposition hair and skin color in mammals ee blocks deposition Labrador retrievers Albinos have no melenin -One gene determines melanin production - One gene determines deposition of melanin Punnett Squares Monohybrid: One trait - 3:1 ratio Dihybrid: Two traits - 9:3:3:1 ratio Incomplete Dominance Codominant Genetic Errors Nondijunction Turner Syndrome - only 45 chromosomes - Females are XO - short, broad chest - undeveloped reproductive organs - 1 in 6,000 Klinefelter syndrome - 47 chromosomes - Males are XXY - No facial hair, breasts enlargement, large hands and feet, long arms and legs - Underdeveloped reproductive organs - 1 in 1,500 Down syndrome - Extra 21 chromosome > 47 chromosomes - Males and females - Short, mental retardation, flat face, upper eyelid fold, abnormal palm creases - 1 in 800 Jacob Syndrome - males are XYY - 1 in 1,000 Triple-X - females are XXX - 1 in 1,500 Edwards syndrome - Trisomy 18 - 1 in 6,000 Patau syndrome - Trisomy 13 - 1 in 15,000 Changes in chromosome structure (Mitosis and Meiosis) Inversion - segment of a chromosome is broken and then flipped 180 degrees - Progeria: progressive genetic disorder that causes children to age rapidly Translocation - rearrangement of parts between no homologous chromosomes - down syndrome (chromosome 21 or 14) - Chronic myelogenous leukemia (chromosome 9 or 22) Deletion - when an end of chromosome breaks off leading to a loss or when two simultaneous breaks lead to the loss of an internal segment - cri du chat syndrome Duplication - the presence of a chromosomal segmentmore than once in the same chromosome - A broken segment from one chromosome can simply attach to its homologue, or unequal crossing-over may occur, leading to duplication in one homologue and a deletion in the other - Huntington’s disease > possess 42 to 120 copies of the sequence CAG in their DNA; a normal person possesses only 11 to 34 copies of the sequence CAG Simple dominant-recessive inheritance Nerurofibromatosis -have a dominant gene located on chromosome 17 that leads to the formation of benign tumors under the skin and in the bones - 1 in 3,000 -caused the disfiguring of Joseph Merrick, “the elephant man” Huntington Disease - Dominant gene located on chromosome - 1 in 20,000 - Causes a progressive neurological degeneration leading to death within 10- 15 years after symptoms appear Marfan syndrome Polydactylism Progeria Familial hypercholesterolemia Autosomal recessive disorders Cystic fibrosis - recessive gene located on chromosome 7 - thick mucus in the - lungs and digestive tract making breathing and digestion difficult - 1 in 2,500 Caucasian births Cystic fibrosis - most common lethal genetic disorder among Caucasians Tay-Sachs disease - gene is located on chromosome 15 - 1 in 3,600 births among eastern European Jews - neurological impairment resulting in blindness, uncontrolled seizures, paralysis and then death by age 5 Phenylketonuria (PKU) - 1 in 5,000 - gene is located on chromosome 12 - Inability to metabolize the amino acid phenylalanine. - If a special diet is not started, mental retardation will result Albinism Blue offspring Galactosemia Incomplete dominance disorders Sickle cell anemia - incomplete dominance. - 1 in 500 African American births. - sickle-shaped red blood cells resulting in poor circulation, anemia, andinternal hemorrhaging Achondroplasia - 1 in 10,000 - Homozygous dominant condition - Stillbirth, but the heterozygous forms are able to mature and reproduce. - Results in type of dwarfism. - Individuals are usually less than 4 feet 4 inches tall X-linked Recessive Inheritance Disorders Duchene Muscular Dystrophy - 1 in 5,000 male births. - muscle weakness that intensifies and usually results in death by age 20 Hemophilia A - 1 in 15,000 male births. - Propensity for bleeding, often internally, due to the lack of a blood clotting factor. - Commonly called “free bleeding” Androgen insensitivity - XY individuals but have female characteristics because they produce an ineffective androgen receptor of the body cells. - Sterile Colorblindness - Inability to distinguish some or all colors5. Fragile X syndrome - 1 in 1500 males in the US. - Mental retardation - A constriction forms in the ends of the X chromosome Genetic Counseling Amniocentesis - a long needle is used to withdraw amniotic fluid containing fetal cells which are tested biochemically or by karyotype Chronic villi sampling - Suction tube is inserted and used to remove cells from the chorion where the placenta will develop. Karyotyping - Cell sample is stimulated to divide and photographed during metaphase. - Staining is done so the banding pattern of the chromosomes is visible. - chromosomes are then paired, counted, and studied to determine if an abnormality exists Pedigree - A char of the genetic connection among related individuals. Gene Expression and Biotechnology Genome: genetic material of a person Gene expression: activation of a gene that results in the formation of a protein - Starts when RNA polymerase transcribes the DNA nucleotide sequence of a gene into a specific mRNA - mRNA migrates to ribosome - translated to specific protein During transcription, a gene is “turned on” Cells use genes to build proteins Cells control when each protein is made by regulating gene expression Proteins - Structural roles - Enzymes - Immune responses Gene Expression Selective gene expression: only a fraction of the genes are expressed at any given time throughout life Cell differentiation: Cells become specialized throughout an organism’s life cycle Morphogenesis: As an organism grows and develops, organs and tissues develop to produce a characteristic form Homeobox: The specific DNA sequence that codes for regulatory genes that determine where certain anatomical structures, such as appendages, will develop in an organism during morphogenesis Non-reproductive cloning: molecular cloning whereby segments of foreign genetic material( recombinant DNA) is incorporated to an organism Reproductive cloning: The process of removing genetic material from a donor egg and then adding an entire genome from another organism Carcinomas: grow in the skin and the tissues that line the organs Sarcomas: cancer of the bones and muscles Lymphomas: solid tumors that grow in the tissues of blood cells Growth factors: regulatory proteins that ensure that the events of cell division happen in the correct sequence and at the correct rate Carcinogens: any substance that increases the risk of cancer Mutagen: an agent that causes mutations to occur within a cell Oncogenes: gene that causes cancer or other uncontrolled cell proliferations Proto-oncogenes: control a cell’s growth and differentiation
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