10/21 - 10/30 weekly bio notes
10/21 - 10/30 weekly bio notes BIOL 1441 - 002
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This 3 page Class Notes was uploaded by Kristin O'Flaherty on Monday November 2, 2015. The Class Notes belongs to BIOL 1441 - 002 at University of Texas at Arlington taught by Shawn Christensen in Fall 2015. Since its upload, it has received 56 views. For similar materials see CELL AND MOLECULAR BIOLOGY in Biology at University of Texas at Arlington.
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Date Created: 11/02/15
1021 CH 12 The cell cycle the net sum of a cell s genetic info is called its genome o in prokaryotes the genome is often a single long circular DNA molecule 0 in eukaryotes the genome usually consists of several long linear DNA molecules prokaryotes bacteria reproduce by a type of cell division called binary fission DNA molecules are packaged into chromosomes 0 chromosomes are made of chromatin a complex of DNA and associated protein 0 the associated proteins maintain the structure of the chromosome and help control gene activity when a cell is not dividing each chromosome is in the form of a long thin chromatin ber a human cells contains about 2m of DNA during cell division the chromatin must condense further 0 before cell division chromatin condenses further coiling and folding to make a smaller package 0 each duplicated chromosome consists of 2 sister chromatids which contain identical copies of the chromosome s DNA 0 the chromatids are initially attached by adhesive proteins along their lengths o as the chromosomes condense the region where the chromatids connect shrinks to a narrow area the centromere 0 later in cell division the sister chromatids are pulled apart 0 once the sister chromatids separate they are considered individual chromosomes each duplicated chromosome has two sister chromatids which separate during cell division every eukaryotic species has a characteristic number of chromosomes in each cell nucleus each single chromosome contains one long linear DNA molecule carrying hundreds or thousands of genes human somatic cells have 46 chromosomes made up of two sets of 23 thus human somatic cells are diploid human gametes have one set of 23 chromosomes human gametes are haploid when a sperm and egg fuse during fertilization a diploid zygote form multicellular organisms depend on cell division for 0 development from a fertilized cell 0 growth 0 repair 0 formation of gametes the cell division process is an integral part of the life cycle of a cell Mitosis a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus typical of ordinary tissue growth Meiosis a type of cell division that results in four daughter cells each with half the chromosome number of the parent cell as in the production of gametes MITOSIS actual cell division consists of mitosis cell division and cytokinesis division of the cytoplasm the cell cycle consists of the mitotic phase and interphase the mitotic M phase of the cell cycle alternates with the much longer interphase cell types differ depending on the amount of time it spends in the G1 phase of Interphase interphase counts for about 90 of the cell cycle 0 interphase has 3 subphases G1 first gap S synthesis and G2 phase second gap chromosomes are duplicated only during the S phase a typical human cell might divide once every 24 hours in late interphase the chromosomes have been duplicated but are not condensed o a nuclear membrane bounds the nucleus 0 the nucleus contains one or more nuclei 0 the centrosome has replicated to form two centrosomes I the centrosome is a nonmembranous organelle that organizes the cell s microtubules M phase includes mitosis and cytokinesis Mitosis includes 5 subphases o Prophase mitotic spindle is composed of centrosomes major driving force in mitosis elements of the mitotic spindle come from partial disassembly of the cytoskeleton the radial arrays of shorter microtubules that extend from the centrosome are called asters centrosomes move away from each other at the start of 1028 prophase the two centrosomes are located near the nucleus by the end of prometaphase the centrosomes are at opposite ends of the cell Prometaphase the nuclear envelope fragments kinetochores assemble on the centromeres Metaphase chromosomes line up making the metaphase plate Anaphase breaks down connection at centromere and pulls chromosomes apart Telophase chromosomes arrive at the poles and the cytoplasm starts to pinch inwards Cytokinesis cytoplasm separates OOOOO interphase has 3 parts 0 G1 checkpoint 1 o S DNA synthesis 0 G2 MPF consists of cyclins which is a protein The activity of cyclins and Cdks uctuates during the cell cycle Since prokaryotes preceded eukaryotes by billions of years it is likely that mitosis evolved from bacterial cell division The sequential events of the cell cycle are directed by a distinct cell cycle control system which is similar to a clock Both internal and external signals feed into the cell cycle checkpoints 0 Internal signals DNA damage incomplete DNA replication 0 External signals densitydependent inhibition cellcell contact anchorage dependence must be attached to a substratum to divide nutrients growth factors 3 major checkpoints found in G1 phase G2 phase and the M phase Cancer cells 0 Don t respond normally to the body s control mechanisms 0 Exhibit neither densitydependent inhibition nor anchorage dependence 0 Form tumors Cancer cells usually continue to divide well beyond a single layer forming a clump of overlapping cells Ch 13 Meiosis and sexual life cycles In asexual reproduction one parent produces genetically identical offspring by mitosis In sexual reproduction two parents give rise to offspring Genes o Are the units of heredity o Are segments of DNA Karyotype is an ordered visual representation of the chromosomes in a cell homologous chromosomes 0 are the two chromosomes composing a pair 0 have the same characteristics 0 may also be called autosomes a diploid cell 0 has two sets of each of its chromosomes 46 total chromosomes a haploid cell 0 has one set of each of its chromosomes 23 total chromosomes human somatic cells are diploid human gametes are haploid human zygote is diploid 1030 TEST REVIEW 1 a aerobic bacterium 2 C where ribosomes are produced A amoeboid movement D A and B 10 C forms peroxide 11 D a and b tubules and actin 12 C Equally distributed 13 A unsaturated fatty acids 14 E passive down 15 A glycosylated surface 16 A rapidly laterally rarely ip 17 A hydrophobic 18 C both A and B 19 D valine 20 A or D electrochemical gradient voltage difference 21 D all of the above 22 23 B glucose plus 602 9 carbon dioxide plus water 24 D delta H 25 A the energy that is able to perform work when temp and pressure is uniform throughout the system 26 C releases energy negative delta G 27 D 30 kcalmol 28 A every energy transfer or transformation increases the entropy of the universe 29 D entropy is the logarithm 30 C prokaryotes that live at predominantly at a particular temp range have evolved such that their enzymes function 31 E decrease the activation energy 32 A feedback inhibition allosteric regulator 33 C L to N 34 E A and D formation of acetyl CoA and electron transport chain 35 C generate NAD for use in glycolysis 36 A substrate level phosphorylation 37 D cytosol of the cell 38 C step f to g and phosphoenolpyruvate 39 C two 40 D fumerate 41 42 43 C 3 44 45 46 47 48 49 50 5 1 52 53 54 55 D taking C out of the gas phase and putting it on a macromolecule 99 89
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