Download Heredity and society exam 2 | BIOL - Human Biology and more Quizzes Human Biology in PDF only on Docsity!
Huntington disease
H = Huntington disease; h = normal Causes damage in brain from accumulation of Huntington protein Symptoms begin slowly ( yrs old) adult-onset disorder Affected individuals may have already had children 50% chance of being affected Progressive neurological signs; Loss of coordination, Involuntary twitching Anxiety, Depression Pneumonia, Loss of speech & swallowing No treatment; Die within 1015 years after symptoms begin TERM 2
Gregor Mendel
DEFINITION 2 European monk in mid-1800s Father of Genetics Using pea plants, he figured out how genes (traits)are transmitted from parents to offspring TERM 3
Traits
DEFINITION 3 distinguishing characteristics plant height and flower color Well defined and unambiguous, no intermediate forms. TERM 4
Allele
DEFINITION 4 variations of a geneHomozygous: organisms that carry identical alleles of agene TT (tall) or tt (short)Heterozygous: organisms that carry non-identical alleles ofa gene Tt TERM 5
Phenotype
DEFINITION 5 what an organism lookslike - tall or short
Genotype
actual genetic makeup -TT, Tt, and tt TERM 7
Wild Type
DEFINITION 7 Most common phenotype TERM 8
Mutant phenotype
DEFINITION 8 A product of a change in the DNA e.g.: defect receptor by mutation of AR gene in CAIsyndrome TERM 9
Mendels Law of Segregation
DEFINITION 9 Two copies of each gene separate from each other during meiosis Only one copy of each gene is present in the sperm or egg, andis contributed to the offspring Each parent gives one copy of eachgene TERM 10
Mendels Law of Independent Assortment
DEFINITION 10 Members of a gene pair segregate into gametes independently A/a and T/t Gametes can have different combinations of parental genes For two traits, four combinations possible in gametes At, at, AT, aT
Cystic Fibrosis
C = normal; c = cystic fibrosis CF affects glands that produce mucus and digestive enzymesthat perform a number of vital functions CF causes production of thick mucus in lungs that blocksairways making difficult to breathe Develop obstructive lung diseases and infections that leads to death Identified CF gene and its protein product (CFTR)mostly in caucasians TERM 17
Sickle Cell Anemia
DEFINITION 17 S = normal red blood cells (RBCs) s = sickle cells RBCs contain a protein of called hemoglobin (Hb) Hb transports O2 from lungs to body tissuesIn SCA, abnormal Hb molecules form rods causing RBCs become crescent- or sickle-shaped Deformed cells are fragile as they circulate along blood vessels, causing anemia and clog small blood vessels and capillaries People with SCA develop heart failure, strokes, and paralysisHigh frequency in areas of West Africa, India, and Mediterranean Seamirrors that of malaria TERM 18
Consanguinity
DEFINITION 18 Inbreeding or cousin marriage Indicated by double line between parents in pedigree A chance that unaffected heterozygous individuals (Aa)marry may be higher than non- consanguineous couple Children have more risk of being affected (aa; homozygous) TERM 19
Neurofibromatosis
DEFINITION 19 N= Neurofibromatosisn n= normal Common trait type 1 NF Many different phenotype Caf-au-lait spots only pigmented spots on skin Noncancerous tumors in the nervous system Tumor can be large and press on nerves causing blindness or paralysisTumors can cause deformities of the face or other body parts (rarely) NF gene has a high spontaneous mutation rate can appear in children of normal parentsnormal parents TERM 20
Adult-Onset Disorders
DEFINITION 20 Disorders develop symptoms only later in life Present problems in pedigree analysis Family members in these disorders may requiregenetic testing because symptoms appear later
Adult polycystic kidney disease
Cysts form in the kidney, but at first, there are few symptoms, often just headache and elevated blood pressure Kidney failure Life-threatening disease In 50% of ADPKD, there is no family history of the disease- spontaneous mutation without either parent being a carrier of the gene May die by age 60 TERM 22
Duchenne Muscular Dystrophy
DEFINITION 22 XM = normal; Xm = muscular dystrophy Disorder that muscles gradually weaken Infants appear healthy, symptoms age ~ years Rapid, progressive muscle weakness Usually must use a wheelchair by age 12 Death, by age ~20 from respiratory infection or cardiac failureDMD gene on the end of X chromosome Encodes protein dystrophin that supports plasma membrane during contraction If dystrophin absent or defective, muscle cells are torn apart TERM 23
Hemophilia A
DEFINITION 23 XH = normal; Xh = affected (hemophilia) Problem in blood clotting danger of non-stop bleeding to death from even minor cut or hemorrhage caused by bruise Clotting factor called factor VIII is absent in blood Hemophilia A most common form of X-linked hemophilia Females affected only if they are homozygous for recessive gene (XhXh), both parents must carry the trait (rare) Now, recombinant DNA technology used to make clotting factors TERM 24
Red-Green Color Blindness
DEFINITION 24 X chromosomes misalign during meiosis in female, resulting in Xchromosomes with too many or too few opsin genes. A son inheriting an X missing an opsin gene is color-blind, while adaughter is a carrier Mostly males affected TERM 25
Mitochondrial Inheritance
DEFINITION 25 Mitochondria Cytoplasmic organelles Important in energy production Have own genes on a circular chromosome Only maternal mitochondria transmitted to all offspring Affected males do not transmit disorder to any of his children
Components of Nucleotides
- Nitrogen-containing Bases2. Five-carbon Sugar3. Phosphate back-bone group TERM 32
Purine
bases
DEFINITION 32 Adenine (A) Guanine (G) TERM 33
Pyrimidine
bases
DEFINITION 33 Cytosine (C) Thymine (T) Uracil (U) TERM 34
Phosphate back-bone group
DEFINITION 34 Links nucleotides Common in both DNA and RNA Phosphate (PO4-) = strong acid Phosphate group of one nucleotide islinked to sugar of another nucleotide Nucleotides form nucleic acid in chainsstructure TERM 35
Organization of DNA Molecules
DEFINITION 35 Double strands of chains connected by base pairs Ladder-like molecule Purine base pairs with pyrimidine base by weak hydrogen bonds A = T or G C Two chains are complementary in base composition Reversed running orientation of two strands 3 5 5 3
Watson-Crick Model
- Genetic information stored in sequence of bases in DNA2. Model offers a molecular explanation for mutation Any change in order or number of bases in DNA canresult in a mutation genetic disorder3. Complementary base sequences in 2 strands of DNAexplains how DNA copies itself Each strand is used as a template to reconstruct thebase sequence in the opposite strand during replication TERM 37
DNA Organization in Chromosome
DEFINITION 37
- Genetic information stored in sequence of bases in DNA2. Model offers a molecular explanation for mutation Any change in order or number of bases in DNA canresult in a mutation genetic disorder3. Complementary base sequences in 2 strands of DNAexplains how DNA copies itself Each strand is used as a template to reconstruct thebase sequence in the opposite strand during replication TERM 38
How Is DNA Replicated?
DEFINITION 38 Before mitosis begins, all cells copy their DNA Each daughter cell receives a complete set of chromosomes Double stranded DNA molecule unwinds Each parent strand serves as a template for complementary new daughter strand Double-stranded DNA molecule unwinds by an enzyme called helicase DNA polymerase Reads sequence of template strand and Links nucleotides together to form complementary strand One old strand (template) + one new daughter strand TERM 39
DNA Replication and Mutations
DEFINITION 39 Replication is not a 100% perfect process,sometimes wrong nucleotides inserted In most cases, DNA polymerase detects error andrepairs mistake If error is not found, mutation results DNA can be damaged by physical or chemicalagents, which causes mutations: UV light can change base pairing in DNA TERM 40
Repair of Mutations
DEFINITION 40 Cells have a number of DNA repair systems If genes responsible for repair systems damaged, errorsare not detected or not fixed properly
Coding region
DNA sequences that encodes amino acidsequence of a protein TERM 47
Non-coding region
DEFINITION 47 DNA sequences that controls when andhow much of a specific protein is madeCoding and Non-coding region on DNA Regulatory region such as enhancer and promoter site DNA sequences b/w gene and gene TERM 48
Nucleus to Cytoplasm
DEFINITION 48 Intermediate called messenger RNA (mRNA) carries genetic information from the nucleus to the cytoplasm TERM 49
Transcription
DEFINITION 49 Double-stranded DNA unwinds and one strand is used as a template to make a complementary mRNA molecule.1. Initiation: RNA polymerase binds to promoter of DNA2. Elongation: RNA polymerase links RNA nucleotides together, forms complementary mRNA3. When RNA polymerase reaches a specific nucleotide sequences (called termination sequence), transcription ends4. RNA polymerase removed from the DNA template strand. mRNA molecule released, DNA strand reforms as a double helix, mRNA is further processed Add cap and poly-A tail Remove introns TERM 50
Translation
DEFINITION 50
- Synthesis of protein from mRNA. Occurs within ribosomes of cytoplasm. The AUG (start codon) encodes for methionine (1st amino acid). The 2nd amino acid is in position, an enzyme forms a peptide bond between two amino acids. The tRNA for the first amino acid is released. The Ribosome moves to next codon and repeats, adding 3rd amino acid to the growing amino acid chain2. Protein (polypeptide) synthesis continues until ribosome reaches astop codons (UAA, UAG, and UGA) which do not code for any amino acid. The Ribosome detaches from mRNA3. Amino acid chain (polypeptide) released, folds into a 3-D structure
Transfer RNA (tRNA)
Function of tRNA: Recognizes and binds to one specific amino acid Recognizes the mRNA codon for that amino acid Structure of tRNA: One end binds a specific amino acid Other end (anticodon: 3 nucleotides) pairs with mRNA codon for specific amino acid TERM 52
Gene Regulation
DEFINITION 52 Human chromosomes contain 20,000-25,000 genes Only 510% genes active at a time Gene expression should be regulated temporally and spatially Gene regulation way of turning genes on and off Regulation can occur at many places: before, during, or after transcription during or after translation TERM 53
Histones
DEFINITION 53 can regulate access to promoter region: If DNA is wound tightly around histone, genes in thatregion are not active If histone is modified or DNA is partly unwound, genesbecome accessible and can be expressed TERM 54
Transcription factors
DEFINITION 54 regulatory proteins Bind to the enhancer or promoter site of non-codingregion of DNA Help RNA polymerase to bind to the promoter Control transcription TERM 55
RNA interference
DEFINITION 55 Small RNA molecules Post-transcriptional regulators of gene expression Prevent mRNA from producing protein (block translation)
Mutagens
Environmental agents called mutagens can alter structureor sequence of DNA Mutations by mutagens induced mutations Mutagens increase frequency of mutations above naturalbackground levelType of mutagens: Physical agents Radiation (natural or man-made): o X-rays, -rays, UV light Chemicals agents: o Nitrous acid formed by digestion of nitrateso EtBr (common lab reagent), Benzene o Tobacco products, vehicle exhaust ... TERM 62
Radiation
DEFINITION 62 Radiation is everywhere Background radiationso Air, food, and from space Man-made radiationso Medical procedure, nuclear testing, nuclear power Radiation forms charged molecules called freeradicals in the cell Free radicals Highly reactive Interact with DNA to produce mutationsRadiation unit = rem, 100,000 rem doses can kill cells1000 mrem = 1 rem Average radiation dose in US 360 mrem / year TERM 63
Base
analogs
DEFINITION 63 Structurally resemble bases in DNA Cause base substitution during replication 5-bromouracil (5-BU) can substitute for T TERM 64
Nitrous acid (HNO2)
DEFINITION 64 Chemicals formed from breakdown nitrates (food preservatives) Can modify the structure of bases in DNA TERM 65
Pesticides
DEFINITION 65 Contain large flat ring Can be inserted in the DNA helix and distort it makes space DNA polymerase may insert extra nucleotide frameshift mutation
Frameshift Mutation
By insertion of a base (A), the next base is shifted Following amino acid sequences altered TERM 67
Identifying Mutation
DEFINITION 67 Mutations recognized by phenotypes.How do we know if mutation is genetic or non-genetic?1. DNA-based genetic test2. Examination of family history by pedigree analysis If it shows that a disorder appeared in family with no history,a new mutation might occur by a mutagen (non-genetic) TERM 68
How are Mutations Repaired?
DEFINITION 68 Cells have repair systems But if repair system is nonfunctional, cellsaccumulate many mutations: Cells stop dividing and become dormant condition(quiescence or senescence ) Control systems can induce cell death (apoptosis) Cell division can escape normal controls (cancer) TERM 69
Repair Systems
DEFINITION 69 Human cells have > 50 genes involved in DNA repair Encode enzymes Monitor and repair DNA damage and mutations DNA polymerase Synthesizes a new DNA strand Proofreads replicated DNA Enzymes repair mismatched DNA Detect errors Remove incorrect nucleotides Insert correct nucleotides Resume replication TERM 70
Epigenetics
DEFINITION 70 Not a mutation but a way to control gene expression Modification of DNA structure but not sequences Some chemical groups may modify DNA or DNA-associatedproteins Epigenetic trait is a stable phenotype Inheritable Epigenome epigenetic state of a cell Modification of histone protein Modification of promoter region of DNA
Angelman Syndrome (Happy Puppet
Syndrome)
Caused by maternal imprinting problem Deletion of long arm of maternal chromosome 15 Symptoms: Severe mental deficiency - absent speech,frequent laughter, and seizures Enlarged tongue that leads to functional and cosmetic problems Marked delays in motor development milestones Puppet-like gait (ataxia) Widely spaced teeth Decreased eye pigment, pale blue eyes TERM 77
Diethylstilbestrol (DES)
DEFINITION 77 synthetic estrogen During 1950s -1970s, used by pregnant woman and thosetrying to get pregnant to prevent miscarriage Caused many problems: Research has identified that three generations were affected by DES treatments
