Biology Exam 3 Revision PDF

10/31/24, 12:12 PM My Files | Knowt exam 3 biology revised the units of heredity and are made up of genes segments of DNA how many chromosomes do humans have in 46 chromosomes (23 pairs) the nucleus of their somatic cells? the two chromo...

10/31/24, 12:12 PM My Files | Knowt exam 3 biology revised the units of heredity and are made up of genes segments of DNA how many chromosomes do humans have in 46 chromosomes (23 pairs) the nucleus of their somatic cells? the two chromosomes in each pair are called... homologous chromosomes/homologs each pair of homologous chromosomes one chromosome from each parent includes... what does meiosis result in 4 haploid daughter cells what does meiosis 1 do separates homologous chromosomes when does crossing over and synapsis occur prophase 1 what does meiosis 2 do separates sister chromatids Mitosis: one division forming 2 identical cells mitosis vs meiosis (clones); Meiosis: two divisions forming 4 genetically different cells meiosis 2 is similar to mitosis because... sister chromatids separate how do different alleles occur through mutation what 3 things contribute to genetic variation crossing over, independent assortment, random fertilization when does independent assortment occur? metaphase I of meiosis random fertilization any sperm can fertilize any egg the mating of 2 true-breeding varieties hybridization p generation true-breeding parents https://knowt.com 1/9 10/31/24, 12:12 PM My Files | Knowt f1 generation hybrid offspring of the P generation f2 generation offspring of the F1 generation alternative versions of a gene alleles the specific spot where a gene resides on a locus chromosome two alleles for a heritable character separate during gamete formation and end up in law of segregation different gametes organism with two identical alleles for a homozygote character organism with two different alleles for a gene heterozygote to determine the genotype, breed the mystery individual with a homozygous recessive testcross individual crossing two true-breeding parents differing in two characters produces ______ in the F1 dihybrids generation, heterozygous for both characters a cross between F1 which can determine whether two characters are transmitted to a dihybrid cross offspring as a package or independently is called? each pair of alleles segregates independently law of independent assortment of any other pair of alleles during gamete formation do genes located near each other on the same yes chromosome tend to be inherited together? occurs when phenotypes of the heterozygote complete dominance and dominant homozygote are identical the phenotype of F1 hybrids is somewhere incomplete dominance between the phenotypes of the two parental https://knowt.com 2/9 10/31/24, 12:12 PM My Files | Knowt varieties two dominant alleles affect the phenotype in codominance separate, distinguishable ways when one gene has multiple phenotypic effects pleiotropy what hereditary diseases are caused by cystic fibrosis and sickle-cell disease pleiotropic alleles when expression of a gene at one locus alters the phenotypic expression of a gene at a epistasis second locus when multiple genes independently affect a polygenic inheritance single trait labrador retriever coat color: one gene example of epistasis determines the pigment color and the other gene determines if the pigment is deposited in the hair example of polygenic inheritance over 180 genes affect height heterozygous individuals who carry the carriers recessive allele but are phenotypically normal recessive disorders show up only in individuals homozygous for the allele ____ example of recessive disorder albinism example of dominant disorder achondroplasia (dwarfism) degenerative disease of the nervous system Huntington's disease (has no effect until the individual is 40 years of age) someone with two x chromosomes is a ___ female someone with one x and one y chromosome is male a ___ a gene that is located on either sex sex-linked gene chromosome is called a https://knowt.com 3/9 10/31/24, 12:12 PM My Files | Knowt is the x or the y chromosome bigger x disorders caused by recessive alleles on the x color blindness, duchenne muscular chromosome in humans are... dystrophy, hemophilia, male pattern baldness x inactivation -in females, one of the X chromosomes is randomly inactivated, and forms a Barr Body genes that are located on the same chromosome tend to be inherited together and linked genes are called... pairs of homologous chromosomes do not nondisjunction separate normally during meiosis results from the fertilization of gametes in aneuploidy which nondisjunction occurred a condition in which an organism has more polyploidy than two complete sets of chromosomes removes a chromosomal fragment deletion repeats a segment duplication reverses orientation of a segment within a inversion chromosome moves a segment from one chromosome to translocation another an aneuploid condition that results from three down syndrome copies of chromosome 21 the result of an extra chromosome in a male, klinefelter syndrome producing XXY individuals turner syndrome monosomy X, sterile females when the phenotype depends on which parent genomic imprinting passed along the alleles for the trait change in genotype and phenotype due to transformation assimilation of foreign DNA https://knowt.com 4/9 10/31/24, 12:12 PM My Files | Knowt DNA is made up of two strands which form a... double helix the phosphate-sugar backbones run in antiparallel opposite directions or are... what does adenine pair with thymine what does guanine pair with cytosine 3 models of DNA replication conservative, semiconservative, dispersive Meselson and Stahl supported which model of semiconservative DNA replication? origins of replication, where the two DNA where does replication begin? strands are separated, opening up a replication "bubble" region at the end of each replication bubble; y- shaped; where new DNA strands are replication fork elongating enzymes that untwist the double helix at the helicases replication forks bind to and stabilize single-stranded DNA single-strand binding proteins relieves the strain of twisting of the double helix by breaking, swiveling, and rejoining DNA topoisomerase strands the initial nucleotide strand RNA primer what synthesizes RNA primers? primase catalyze the synthesis of new DNA at a DNA polymerase replication fork each nucleotide that is added to a growing nucleoside triphosphate DNA strand is called a _____ supplies adenine to DNA and is similar to the dATP ATP of energy metabolism https://knowt.com 5/9 10/31/24, 12:12 PM My Files | Knowt which direction is the new strand synthesized 5' to 3' the lagging strand is synthesized as a series of okazaki fragments segments called... what joins okazaki fragments DNA ligase Binds to and stabilizes single-stranded DNA single-stranded binding protein until it can be used as a template Using parental DNA as a template, synthesizes new DNA strand by adding nucleotides to an DNA polymerase III RNA primer or a pre-existing DNA strand Removes RNA nucleotides of primer from 5' end and replaces them with DNA nucleotides DNA polymerase I added to the 3' end of adjacent fragment DNA repair enzymes correct errors in base mismatch repair pairing nuclease cuts out and replaces damaged nucleotide excision repair stretches of DNA the process by which DNA directs protein synthesis, includes two stages: transcription gene expression and translation the synthesis of RNA using information in transcription DNA; creates mRNA is the synthesis of a polypeptide, using translation information in the mRNA where does translation occur ribosomes what separates transcription from translation nuclear envelope RNA transcripts are modified through ______ RNA processing to yield the finished mRNA the initial RNA transcript from any gene prior primary transcript to processing https://knowt.com 6/9 10/31/24, 12:12 PM My Files | Knowt the concept that all cells are governed by a cellular chain of command: DNA->RNA- the central dogma >protein triplets of nucleotides that specify amino acids codons of the 64 triplets, 61 code for____ and 3 are amino acids, stop signals ____ RNA synthesis is catalyzed by... RNA polymerase The RNA is _____________ to the DNA complementary template strand What base is found on RNA in place of thymine uracil in which direction is RNA transcribed 5' to 3' in bacteria, the polymerase stops transcription at the end of the ____ and the mRNA can be terminator translated without further modification in eukaryotes, RNA polymerase II transcribes the _____ ; the RNA transcript is released 10- polyadenylation signal sequence 35 nucleotides past this _____ after transcription, pre-mRNA is modified RNA processing through ___ in modification, the 5' end receives a ____ and 5' cap, poly-A tail the 3' end gets a _____ what are the functions of the 5' cap and the Facilitate the export of mRNA to the cytoplasm, poly-A tail Protect mRNA from hydrolytic enzymes, Help ribosomes attach to the 5′ end RNA transcripts have long noncoding stretches of nucleotides that lie between introns coding regions, called https://knowt.com 7/9 10/31/24, 12:12 PM My Files | Knowt the part of the transcripts that are actually exons expressed are called removes introns and joins exons, creating an mRNA molecule with a continuous coding RNA splicing sequence RNA splicing is mostly carried out by... spliceosomes catalytic RNA molecules that function as ribozymes enzymes and can splice RNA it can form a three-dimensional structure because of its ability to base-pair with itself, three properties of RNA enable it to function some bases in RNA contain functional groups as an enzyme that may participate in catalysis, RNA may hydrogen-bond with other nucleic acid molecules genes can encode more than one kind of polypeptide, depending on which segments alternative RNA splicing are treated as exons during splicing transfer amino acids to the growing tRNA polypeptide in a ribosome; aids in translation first step of transcription: a correct match between a tRNA and an amino acid must be aminoacly-tRNA synthetase made by the enzyme... second step of transcription: correct match between the tRNA anticodon and an mRNA codon what are the large and small ribosomal protein and rRNA subunits made of what are the 3 binding sites for tRNA P, A, E holds the tRNA that carries the growing P site polypeptide chain holds the tRNA that carries the next amino A site acid to be added to the chain https://knowt.com 8/9 10/31/24, 12:12 PM My Files | Knowt the exit site, where discharged tRNAs leave E site the ribosome 3 stages of translation initiation, elongation, termination elongation occurs in 3 steps: codon recognition, peptide bond formation, and translocation synthesize proteins that function in the cytosol free ribosomes make proteins of the endomembrane system bound ribosomes and proteins that are secreted from the cell https://knowt.com 9/9