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Biology test 4 K
meiosis, protein synthesis, genetics
| Question | Answer |
|---|---|
| Central Dogma of Sciene | DNA>>RNA>>>Protein |
| Transcription | process of generating RNA (RNA synthesis) from DNA template occurs in the nucleus |
| Messenger RNA | template for protein synthesis |
| Ribosomal RNA | makes up structure of ribosomes |
| Transfer RNA | transports amino acids to ribosomes during protein synthesis |
| Translation | the process of generating protein from RNA template; occurs in the cytoplasm |
| TH morgan | first assigned genes to specific loci(locations) on chromosomes |
| GENE | but later a gene was saw as a specific nucleotide sequence along DNA Functional definition |
| Formal definition | a region of DNA that is expressed (produced) to produce a final function product that is either a polypeptide or RNA molecule |
| Promoter | DNA sequence where RNA polymerase attaches and starts transcriptions promotes transcription |
| Terminator | series of nucleotides that tells or signals end of transcription |
| Transcription Unit | Genes that codes RNA (template) |
| Coding Strand | strand that sued as the blueprint(template strand) Non |
| RNA Polymerase | puts together nucleotides to put together RNA; synthesizes RNA; 3 types; synthesizes mRNA |
| RNA | single stranded; complementary to DNA template; 5 to 3 direction; A, U, G, C |
| Start Point | where transcription begins |
| Transcrition Factors | proteins that help binding of RNA polymers |
| Transcription Initiation Complex | RNA Polymerase + Transcription Factors |
| TATA box | series of 25 nucleotides; very beginning |
| Steps of transcription | 1 RNA polymerase binding; 2 Elongation of RNA Strand; 3 Termination |
| Polymerase binding | RNa poly binds with transcription factors then transcription factors bind TATA box |
| Elongation of RNA | RNA polymerase moves along DNA and unwinds, RNA polymerase adds nucleotides to 3 end, new RNA peels off and DNA reforms; multiple RNA polymerase can attach to one Gene |
| Termination | different in prokaryotes and eukaryotes; In eukaryotes Polyadenylation Signal signals the end and approximately 35 nucleotides later proteins cut off the RNA transcript and is now PRE |
| Pre | mRNA |
| Pre | mRNA steps |
| Guanosine cap | G bases added to first 20 |
| Add a Poly A Tail | tail end of messenger RNA; 50 |
| Removal of Introns | transcriptual unit averages 2700 basae pairs long; only 1200 nucleotides needed to code for an average protein; introns and exons; introns are removed and neighboring exons are spliced together |
| Introns | regions not translated into proteins |
| Exons | regions that are codes for amino acids |
| Small Nuclear Ribonuclear Proteins | recognize splice sites and form a spliceosome |
| Ribozymes | (made of RNA) cut the iron |
| Spliceosome | joins the ends of the two exons |
| Genetic Code | relation of RNA and amino acids in proteins;4 bases in triplets(condons) with 64 possible condons; only 20 amino acids |
| Condon | 3 base sequence on the mRNA |
| Anticodon | 3 base sequence on the tRNA that are complementary to the condon |
| Start Condon | always AUG methianinie |
| Stop condon | (three) do not code for amino acids |
| Components of translation | mRNA, small and large ribosomal subunits, amino acids, tRNA , amino acyl tRNA synthase, Initiation factors, elongation factors, release factors |
| Cytoplasm | a pool of ribsosomal subunits exist in this; subunits do not come together until translation begins |
| Ribosomes | cells contain thousands of these; act as enzymes catalyzing peptide bonds formation between amino acids to form proteins |
| Antibiotics | target bacterial ribosomes so they cannot make proteins |
| tRNA | complementary regions from H bonds to stabilize structure into the shape of a T; can only carry one amino acid at a time |
| amino acids | for translation is attached to the 3 prime |
| Anticodon | is on the 5 prime end in translation |
| Charging of tRNA | amino acid attached to tRNA; done by amino acytl tRNA synthase; ATP driven |
| Amino actyl tRNA synthase | enzyme that puts the proper amino acid on the proper tRNA |
| Initiation | starts at first AUG |
| Elongation | amino acids added |
| Termination | ends at a stop condon |
| Initiation steps | small sub binds the mRNA, subunit moves along the mRNA until the first AUG, large subunit binds, tRNA adds the amino acid Meth by binding the P Site of the large subunit, another tRNA with the next amino acid binds tot the A site of the larger subunit |
| Elongation steps | P and A sites are filled, amino acid is transferred from P to A, empty tRNA moves from P to E site then leaves the ribosome, tRNA in A site is moved to the P site to condon, vacant A for repeat elon One elongation cycle= about a 10 of a second in bacteria |
| Termination step | A stop condon is recognized, no tRNA binds the A site, Release factor binds to the A site and cause additction of a water molecule instead of another amino acids, protein is freed through the Exit tunnel, and ribosome complex dissociates |
| Polyribosomes(polysomes) | multiple ribosomes that can attach to a single mRNA for protein synthesis; allows production of much more protein from a single mRNA |
| Mutation | A rare change in base pairs of DNA ultimately creating genetic diversity |
| Point Mutaitons | chemical changes in just one base pair of a gene |
| 2 types of point mutation | substitiutions, deletions/insertions |
| Substitions | replacement of one base pair in the complementary DNA strand |
| Silents mutation | DNA is translated into the same amino acid; because of the repetition of genetic code may be no effect |
| Missense Mutation | codes for an amino acid, but not the proper tone |
| Nonsense Mutation | DNA changes to a stop condon;nearly all lead to a nonfunctional protein |
| Insertions | addition of base pairs |
| Deletions | loss of base pairs |
| Reading frame | condon (triplet) organization; Insertions and deletions alter this |
| Mutagens | Physical and chemical agents that interact with DNA to cause mutations |
| Physical mutagen | CUV light causes disruptive thymine dimers |
| Chemical(base analogues) | chemicals similar to DNA base pairs that insert into the DNA during replication and distort the helix |
| Carciongens | most mutagens are cancer causing chemicals |
| Meiosis | Process that results in one half of the number of chromosomes (aka Reduction of Ploidy) |
| 46 | how many chromosomes in every human cell? |
| Homologous pair | pair of chromosomes 23 pairs, each member of a pair is called a homologue; one maternal and on paternal; 22 pairs are called autosmoes |
| Pair 23 | sex chromosome; determines sex of individual |
| Germ cells | cells that have the potential to become eggs and sperm as a result of meosis |
| Gametes | eggs and sperm are called |
| Karyotype | number and apperence of chromosome in a eukaryotic cell |
| Karyology | study of chromosome sets |
| Colchicine | stops mitosis by inhibiting spindle fibers |
| Ploidy | the number of homologues in the cells of an organism |
| Diploid | in humans two sets of 23=46 |
| Haploid | in humans on set of 23 |
| 46 Chromosomes | in every human cell; pair by 23; each pair is a Homologous Pair Each member of the pair is called a Homologues pair; One homologue is Maternal and the other Paternal Paired by size #1 largest & # 22 smallest |
| Autosomes | The 1through 22 pairs are |
| Chromosome 23 | determines the sex |
| Meiosis | Germ cells undergo Meiosis 1 46 chromosomes reduced to 23 2 2n to 1n 3 Reduction of ploidy 4 Purpose 23 in egg + 23 in sperm yields 46 5 Germ Cells undergo meiosis to 6 takes place in ovaries in women and testes in men |
| Prophase 1 | Condensation of chromatin 1 Euchromatin to Heterochromatin 2 Pairing of Homologues 3 Loss of the nuclear envelope |
| Subset stages of Prophase 1 | Leptotene Zygotene Pachytene Diplotene Diakinesis |
| Leptotene | chromatin condensation. |
| Zygotene: Pairing of homologues Synaptonemal Complex formed – protein “ladder” connecting homologues Pachytene – Crossing Over occurs – cutting and pasting (exchange) between homologues Pachytene | inner parts of the two homologues participate;; Homologues are now called Tetrads;Some of the maternal DNA is exchanged with the paternal DNA forming new Linkage Groups; Crossing Over ultimately results in Recombination of genes |
| Linkage Groups – genes on chromosomes that travel together during meiosis Synapsis | Homologues closely associate |
| Recombination Nodules form – contain enzymes to perform the cutting and pasting Diplotene | Partial decondensation of chromatin; Heterochromatin to Euchromatin; Opens up the DNA for Transcription; Why? The embryo does not start producing its own proteins right away and needs them from the egg |
| Diakinesis | The partially decondensed chromatin recondenses for the remainder of meiosis Metapahse 1 |
| Anaphase 1 | Contraction of Spindle Fibers results in separation of homogues; Homologues are pulled to opposite poles of the cell |
| Telephase 1 | Movement of the homologues has stopped; Then have cytokinesis and the cell immediately enters Meiosis II; In some species there is a partial decondensation of chromatin and re |
| Prophase 2 | If , in some species, the chromatin is partially decondensed: Chromatin recondenses; Nuclear envelope disappears |
| Metaphase 2 | A spindle fiber binds to each chromatid; Chromosomes line up on the Metaphase Plate |
| Anaphase 2 | Each sister chromatid is separated and moved to opposite poles of the cell |
| Telophase 2 | Movement of chromatids has stopped; Chromatin decondenses back to heterochromatin |
| Cytokinesis | Cytokinesis occurs just like in mitosis; Now have 4 haploid cells; In males the 4 cells will mature into 4 sperm cells; In females 3 of the cells will degenerate and 1 will mature into an egg |
| Three results of Meosis | Reduction of Ploidy (2n to 1n) Independent Assortment of maternal and paternal homologues Formation of New Linkage Groups due to crossing over |
| Females differences | Germ cells divide prenatally Germ cells remain at that stage until puberty and ovulation At ovulation, meiosis proceeds to Metaphase II and arrests At fertilization, meiosis finishes Women are born with 2 million eggs,at puberty have 400,000 |
| Males difference | Males Germ cells divide prenatally (by mitosis) then stop and do not enter meiosis until puberty The germ cells have the ability to continue mitosis at puberty so there is always a supply of sperm throughout the male lifetime |
| Blending Hypothesis – | genetic material from both parents mix (ie both red and green). |
| Particulate Hypothesis – | parents pass on (genes) that retain their separate identity in their undiluted form • This hypothesis is currently accepted • Gregor Mendel developed his theory mid 1800’s Mendel was a monk who studied math and crossing pea plants |
| Character | a heritable feature that varies among individuals, such as flower color. |
| Trait – | each variant for a character, such as white or purple flowers. |
| Hybridization – | crossing of true breeding varieties. |
| True | breeding – over many generations, the offspring produce the same variety as the parent True |
| Alleles | The gene for flower color exists in two forms |
| Mendels Model | Explained the 3:1 ratio of purple to white For each character, an organism inherits 2 alleles; One allele from one parent, one allele from the other parent |
| The Dominant allele | determines appearance |
| The Recessive allele | has no noticeable effect on the organism’s appearance |
| Mendel’s Law of Segregation | The two alleles for a heritable character separate during meiosis Egg and sperm then have one allele for a character so at fertilization the product is two |
| Mendel’s Law of Independent Assortment | Each pair of alleles separate independently of one another during meiosis |
| Punnett Squares | Named after Reginald Punnett; Used to predict allele composition of offspring; The cross must be between parents of known genetic makeup |
| Dominant Allele | Capital Letter |
| Recessive Allele – | lower case letter. |
| Homozygous – | pair of identical alleles controlling a character. |
| Heterozygous – | two different alleles. |
| Genotype – | an organisms genetic makeup. |
| Phenotype – | an organism’s observable trait. |
| Monohybrid Cross – | cross following a single character . |
| Dihybrid Cross – | cross following more than one character;Alleles for different characters sort independently from one another following Mendel’s Law. |
| Complete Dominance – | Follows classic Mendelian Genetics; F1 offspring always appear like one of the two parental varieties. |
| Incomplete Dominance – | Neither allele is completely dominant; F1 has a phenotype that is somewhere between the two varieties. |
| Co Dominance | Two alleles both affect the phenotype in separate and distinguishable ways |
| Pleiotropy | When a gene has multiple phenotypic effects ;Greek; Pleion=more, Tropi=turn Multiple symptoms associated with hereditary diseases Examples: Cystic Fibrosis Sickle Cell Disease |
| Epastasis | A gene at one locus alters or controls the phenotypic expression of a gene at another locus |
| Multifactorial – | many factors, genetic and environment affect phenotype. |
| Recessive inherited disorders | Albinism and Cystic Fibrosis |
| Recessive alleles in diseases either produce: | Malfunctioning protein, or No protein at all. |
| Heterozygotes | do not exhibit the disease because they produce enough of the normal protein |
| Disease manifests in | homozygous recessive genotypes |
| Carrier | Heterozygotes may transfer a disease alleles to their offspring |
| Friedreich’s Ataxia | progressive damage to nervous system; gait and speech problems |
| Usher Syndrome – | hearing loss or deafness and vision loss. |
| Tay Sachs Syndrome – | mental/physical deterioration; die by age 4. |
| Cystic Fibrosis | Most common lethal genetic disorder • Normal allele produces a chloride ion the mucus coat on cells is thicker and builds up in lungs/other organs • Usually die by age 5 from infections/clogged airways |
| Sickle Cell Disease | • Affects 1 of 400 people of African descent • Caused by a substitution of a single amino acid of the hemoglobin protein in RBCs • With disease, hemoglobin forms abnormal shapes making the RBCs sickle |
| Red | green colorblindness |
| Duchenne’s Muscular Dystrophy – | progressive weakening of muscles. |
| Hemophilia – | absence of a protein required for blood clotting. |
| Sex linked genes | Are on the X chromosome; Each parent donates one chromosome to offspring; fathers to daughters only; mothers to sons or daughters |
| dominant alleles | Result of these are Much less common than recessive disorders |
| Achondroplasia | A specific type of dwarfism; Rare because most are homozygous recessive |
| Huntington’s Disease | A degenerative disease of the nervous system; Symptoms manifest after reproductive age (35 |
| Multifactoral Diseases | A disease with a genetic component in addition to a significant environmental influence |
| Polygenic – | controlled by many genes; many multifactorial genes are. |
| Amniocentesis | Extract small amount of amniotic fluid; Disease determined by chemicals present or karyotype |
| Chorionic Villus Sampling | Tissue sample from placenta (Membrane that unites fetus with uterus) ;in fetal testing |
| Amnion | is the inner membrane |
| Chorion | is outer membrane |
| Villi | are structures that protrude from chorion |
| Fetoscopy | Needle thin tube with light/scope inserted into uterus |
| Phenylketonuria (PKU) | Recessively inherited in 10,000 – 15,000 births; Cannot properly metabolize phenylalanine; Phenylalanine and its byproduct accumulates in blood & causes mental retardation; Blood is tested for the enzyme that metabolizes phenylalanine. |
| Genetic Imprinting | One gene on one chromosome is silenced while its allele on the homologue is left free to be expressed; Most imprinted genes are critical for embryonic development where one allele is needed and not both |
| Status of imprinting | depends on whether the gene is present in the male or female |
| Mendelian Genetics | is different in imprinting bc it does not matter if the dominant or recessive allele is donated from either parent |
| Approximately ____ imprinted genes have been identified in mammals | 36 |
| Methylation | silences the allele that is not expressed |
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