Exam 3 Study Guide
Exam 3 Study Guide BIOl 1020-003
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This 7 page Study Guide was uploaded by Crystal Boutwell on Wednesday November 4, 2015. The Study Guide belongs to BIOl 1020-003 at Auburn University taught by Dr. Zhong in Fall 2015. Since its upload, it has received 99 views. For similar materials see Principles of Biology in Biology at Auburn University.
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Date Created: 11/04/15
EXAM 3 STUDY GUIDE CHAPTER 12 MITOSIS A B C F1 Chromatin the complex of DNA and associated proteins Chromosome is more condensed Gametes sexual cells have one set of chromosomes and somatic cells nonsexual cells have 2 sets of chromosomes Animals have 46 chromosomes total which 23 pairs Sister chromatids are identical and created during the replication process of the S phase of Mitosis They are held together by cohesion and joined by a centromere Mitosis is division of the nucleus alone and cytokinesis is division of the cytoplasm Interphase exists anytime mitosis is not happening Interphase consists of 3 phases a G1 phase cell growth b S phase DNA replication c G2 phase more cell growth to prepare for mitosis What controls chromosomal movement during mitosis The mitotic Spindle which is produced from centrosomes a Kinetochores where the spindle fiber connects to the chromosomes VERY VERY IMPORTANT Steps of Mitosis a Prophase i First time individual chromosomes can be observed ii Mitotic spindle is formed iii Centrosomes move away from each other as the spindle fibers between them lengthen b Prometaphase usually linked with prophase i Nucleur envelope fragmetns ii Some spindle fibers attach to kinetochores c Metaphase i The centrosomes are finally at opposite ends of the cell ii All of the chromosomes line up at the metaphase plate an imaginary line at the center of the cell iii Kinetochores officially attach to all chromosomes 1 Keep in mind each sister chromatid has a kinetochore So there are two one each chromosomes 1 Anaphase i Shortest stage of mitosis ii Sister chromatids are pulled apart and towards opposite ends of the cell The spindle bers reel them in like shing e Telophase i Two daughter nuclei form ii Remaining spindle fiber microtubules are destroyed iii Mitosis officially ends 1 Cytokinesis i In animal cells a develops as the cell is pinched into two daughter cells ii In plant cells a forms and connects to the cell wall creating two daughter cells I Binary fission is the term given to the replication of cells in bacteria J The cell cycle control system monitors cyclic changes in regulatory proteins to work as a clock a Specific checkpoints exist in the cycle where a cell will stop until it gets the go ahead to continue with the division process Occur in the G1 G2 and M phases K Most cells die or stop dividing but cancer cells are immortal and will not quit dividing ever L Malignant tumors do remain in the same place They may undergo metastasis and export cancer cells to other sites other than where they began CHAPTER 13 MEIOSIS A A gene is a genetic code B A locus is the location on a chromosome that a specific gene is at C Asexual reproduction involves a single parent who has genetically identical offspring D Sexual reproduction combines genes from two parents leading to genetically diverse offspring E Somatic cells are diploid 2n They have two sets of every chromosome Humans have 46 chromosomes total in each cell Two sets of 23 F Homologous pairs are two chromosomes that did not come from the same parent but which have genes lined up at the same locus G Sex chromosomes are either XX female or XY male H Gametes are sex cells They are produced by meiosis and are haploid n23 I Fertilization takes two gamete cells 1 sperm and 1 egg and creates one diploid zygote which develops into an organism J Meiosis is two cell divisions a Meiosis I separates the homologous chromosomes i 3 things that makes meiosis I and mitosis different 1 Prophase 1 Each homologous pair undergoes between nonsister chromatids with the subsequent appearance of chiasmata a Synapsis is the pairing up of two homologous chromosomes Crossing over is whenever the legs of one chromosome crosses the leg of the other and they exchange information Chiasmata is the area where crossing over took place 2 Metaphase I chromosomes line up as homologous pairs on the metaphase plate a There are multiple ways the chromosomes could have lined up 3 Anaphase IHomologs separate from each other sister chromatids remain joined at the centromere b Meiosis II separates the sister chromatids Meiosis produces 4 daughter cells 1 What three events in sexual reproduction contribute to genetic variation in a 0 population i Independent assortment of chromosomes during meiosis I ii Crossing over during meiosis I iii Random fertilization of eggs by sperm CHAPTER 14 MENDEL AND THE GENE IDEA A B mun Gregor Mendel Law of segregation genes have alternative forms alleles This explains that during meiosis the two alleles that each organism carries for a certain gene will separate One allele goes to one gamete One allele goes to another gamete Heterozygote the two alleles are different Homozygous the two alleles are the same Dominant allele is the one expressed recessive allele is the one carried but usually not seen unless it is homozygous recessive aa Law of independent assortment the pair of alleles for a given gene segregates into gametes independently of the pair of alleles for any other gene This basically just means that hair color and eye color do not travel from your mom to you together If you happen to have the same hair and eye color as your mom it s by random assortment No two genes travel together According to this law Multiplication rule the probability of two events occurring together is equal to the product of individual probabilities of the independent single events So if you have a 14 chance of having green eyes and a IA chance of having blonde hair then you have a IA M1 18 chance of having green eyes and blonde hair at the same time Addition rule the probability of an event that can occur in to or more independent mutually exclusive ways is the sum of the individual probabilities So basically this just means that if one combination of alleles between mom and dad gives a kid brown hair and another separate combination of alleles between mom and dad would also give the kid brown hair then the total probability of the kid having brown hair is the sum of those combinations a These rules come in handy when you are comparing more than one gene I BUT Mendel didn t always get everything right It would be a million times simpler if dominant genes were always dominant and recessive genes were always recessive But it doesn t work like that in the real world soooo a ONE GENE i Complete dominance When the phenotypes that s just what the organism looks like Think Physical appearance Phenotype of an organism that is Heterozygous Aa and an organism that is Homozygous dominant AA look exactly alike Basically carriers do not express the gene they carry ii Incomplete dominance Whenever the organism is heterozygous it is a mixture of the dominant and recessive alleles So if red owers are dominant and white owers are recessive AA would be red aa would be white and Aa would be pink iii Codominance Basically the same as above Say you have a ower bush If all of the owers were Aa then half of the owers would be red and half of them would be white iv Multiple Alleles That just explains that unlike pea plants most genes that an organism carries has more than two possibilities for their alleles v Pleiotropy This is whenever one gene will effect several other phenotypes So for example sicklecell disease The gene doesn t just mess up the cells it also effects other physical characteristics about the person with the disease b MORE THAN ONE GENE i Epistasis Whenever one gene is expressed in a phenotype it effects whether or not the other genes is expressed In labs despite whether or not a dog is dominant for black fur or brown fur if they are dominant for a certain pigment gene then their fur will have no color at all ii Polygenic Inheritance Basically the opposite of the above Instead of one gene affecting all other genes it occurs whenever a bunch of genes affect just the one gene An example of this is skin color J Multifactorial characters are effected by the environment K Pedigrees are genetic family trees They help you determine who has what gene and what the genetic makeup of members of a family are a Squares are boys circles are girls b Filled in shapes are members who are affected empty shapes are people who are not effected c People who are homozygous for a recessive trait generally come from parents who are both heterozygous carriers CHAPTER 15 THE CHROMOSOMAL BASIS OF INHERITANCE A Chromosome theory of inheritance genes are located on chromosome the behavior of chromosomes during meiosis accounts for Mendel s laws B Sex chromosomes carry sexlinked genes more genes on the X chromosome than the Y a SRY required for the development of testes Ylinked gene b Any male that inherits a recessive Xlinked allele from his mother since boys cannot receive X alleles from their father who must give them a Y will express the trait c Females on the other hand need to contain both Xlinked alleles to express the recessive trait d In females one of the two X chromosomes is randomly deactivated in development and becomes a barr body C Linked genes tend to be inherited together because they are located near each other on the chromosome a The alleles of unlinked genes are either on separate chromosomes or so far apart on the same chromosome that they assort independently b Parental types will have the same combination of traits as those in the P generation If one of the parents has black hair and red eyes and hair and eyes are linked genes then at least one of the kids will have black hair and red eyes together c Recombinant types exhibit new combinations of traits that have not been seen in the P generation d The farther apart genes are the more likely their allele combinations will be recombined during crossing over D abnormal chromosome number a Can be caused by nondisjunction Whenever homologs or sister chromosomes do not separate during meiosis b Results in Polyploidy more than two complete sets of chromosomes i Trisomy 2n 1 The organism has one extra chromosome plus the normal two sets of chromosomes ii Monosomy 2n1 the organism is missing one chromosome from having the normal two sets of chromososmes E When chromosomes break the results can be alterations of the chromosome structure a Deletions removes a chromosomal segment i ABCIEFGH 9 ABCEFGH b Duplication repeats a segment i ADEFGH 9 ABCDEFGH c Inversion reverses a segment within a chromosome i AEFGH 9 AEFGH d Translocation moves a segment from one chromosome to a nonhomolgous chromosome In reciprocal translocation nonhomologous chromosomes exchange fragments F Changes to a chromosome can affect the phenotype and lead to disorders a Down syndrome trisomy of chromosome 21 b Certain cancers G Genomic imprinting whenever it matters whether or not a gene came from mom or from dad CHAPTER 16 MOLECULAR BASIS OF INHERITANCE A Experiments with phages or bacteria provided the rst strong evidence that the genetic material is DNA B DNA is a doublehelix this was discovered by Watson and Crick a The two strands of DNA run in opposite directions 3 5 and 5 3 C DNA replication is semiconservative This means that each of the strands of the old DNA acts as a template for the new DNA D Replication begins at an origin of replication Bacterial chromosomes have one of these but eukaryotes have several Proteins open up the DNA separating the strands making a bubble E Replication proceeds in both directions from the origin of replication At each end of the bubble is a replication fork 4 Overall direction of replication umII g V I Lk LIE n Yy quotw39 l39ql Yo LJHL x39 z 39 1 l J 1 uTW39 quotn Y3939 ailquotf I39m gtA IPk 39 A Y quot 39 J quot quotI t 39 r 439 1 Erlfn39vl gt A Hlal I llYOl DNA pol Ill Leading strand 5 Replication fork DNA quot9859 DNA poll Pflmase La a 2 Parental DNA DNA llll 99mg 3quot 399 Primer p0 strand 3 351quot 39 39 39l quot3 3 5 39 39 quot 5 o quot 39 a quot k 39 4n39 quot J t F STUDY THIS PICTURE AND KNOW IT AND THE ROLES OF THE PROTEINS a DNA is replicated in the 5 3 direction This is important in the differences between the leading strand and lagging strand When looking at the replication fork opening to the RIGHT the leading strand is on top and the lagging strand is on the bottom If it opens to the LEFT the leading strand is on bottom and the lagging strand on top Remember that replication goes in BOTH directions from the origin of replication So there will be TWO replication forks in one bubble Topoisomerase not pictured relieves the strain of unwinding the DNA Goes above the replication fork Helicase the green one enzymes that unzip the double helix at the replication forks Singlestrand binding proteins SSBP The little grey things bind to the unpaired DNA strands to keep them from pairing up again Primase synthesizes RNA primer the building block of the new strands of DNA Leading Strand i Primase puts primer at the 3 end DNA pol III attaches to the end of the primer and adds nucleotides one by one in the 5 3 direction of the NEW strandSynthesizes DNA in the direction of the replication fork Lagging Strand i Builds the new DNA strand away from the replication fork ii Primase joins RNA primer to the parent DNA iii DNA pol III adds DNA nucleotides to the primer making Okazaki fragments iv After reaching the next RNA primer to the right DNA pol III detaches V The process continues behind the first primer vi DNA pol I replaces the RNA with DNA vii Ligase forms a bond between the newest DNA and the DNA of fragment 1 DNA polymerases proofread DNA and replace errors Nucleotide excision repair is a process by which nucleases cut out and other enzymes replace damaged stretches of DNA The ends of eukaryotic chromosomal DNA get shorter with each round of replication Telomeres repetitive sequences at the ends of linear DNA molecules postpone the erosion of genes Chromatin packing order nucleosomes 30nm fiber looped domains Chromosome a b c d Histones proteins that DNA wrap around to form nucleosomes the most basic units of DNA packing This packs together to form a 30nm fiber Fibers loop structurally to create looped domains Looped domains coil and foil in a manner to create a chromosome Interphase cells have two types of packing a b Euchromatin less compacted accessible for transcription of genes Heterochromatin highly condensed not accessible for transcription of genes
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