Chapter 1 List processes needed for the spontaneous origin of life simple molecules must polymerize assemble into polymers a b origin of self replicating molecules formation of self replicating molecules c d non living synthesis of simple organic molecules simple molecules must become isolated from the surroundings enclosed in membranes Outline the role of prokaryotes in the development of an oxygen rich atmosphere on the Earth a early atmosphere was oxygen free b some prokaryotes could carry out chemosynthesis c cyanobacteria and other varieties developed the ability to photosynthesize d used water as hydrogen source so released oxygen e oxygen began to accumulate in the atmosphere f more photosynthesis than respiration g atmosphere changed from a reducing atmosphere to an oxidizing atmosphere h current life forms depend upon an oxygen rich atmosphere Outline the use of human embryonic stem cells hESC to treat Stargardt s disease a an inherited form of degeneration of retinal layer photoreceptor cells blindness eye genetic disorder b hESC stem cells can provide differentiate into healthy retinal cells c injecting hESC stem cells into the retina eye can restore vision in animal human trials Outline the cell theory a living things are composed of cells b cells are the basic smallest unit of life c cells come from pre existing cells Discuss the endosymbiotic theory for the origin of eukaryotes a mitochondria chloroplasts were once independent prokaryotes b microorganisms prokaryotes taken into cell by endocytosis c this larger host cell was heterotrophic free living prokaryote not digested d kept inside cell and perform respiration photosynthesis e new living arrangement mutually beneficial depend on each other to exist as single organism f ancestral eukaryote cell and engulfed prokaryote reproduce as a unit by binary fission the engulfed prokaryote provides energy by aerobic respiration for the eukaryote g prokaryote gains protection nutrition h developing into mitochondria chloroplasts i mitochondria chloroplasts have double membranes suggests engulfing by endocytosis j mitochondria chloroplasts have circular naked DNA as prokaryotes k mitochondria chloroplasts have 70S ribosomes as prokaryotes l mitochondria chloroplasts grow and divide like prokaryotic cells m similar size and shape or mitochondria chloroplasts to prokaryotes n mitochondria and chloroplasts cannot survive on their own p cristae similar to mesosomes thylakoid have similar structures in prokaryotes q but theory cannot be falsified as it predicts something occurring in the past r theory does not explain the origins of cilia flagella linear chromosomes meiosis s weaker evidence that cilia flagella evolved from attached bacteria spirochetes Explain the importance of surface area to volume ratio as a limit to cell size a as volume of a cell increases the ratio of its surface area to volume decreases rate of exchange of materials gas energy is a function of its surface area b food oxygen enters through the surface of cells c d wastes leave through the surface of cells e more metabolic activity in a larger cell means more food and oxygen required f g at low surface area to volume ratios exchange of materials takes longer reduced rate of production of heat waste resource consumption is a function of its volume efficiency of exchange vice versa large volume means longer diffusion time large volume means more wastes produced excess heat generated will not be lost efficiently with low surface area to volume ratio h i j k eventually surface area can no longer serve the requirements of the cell l m thus the size of the cell is reduced and kept within size limits this critical ratio stimulates mitosis Describe the characteristics of stem cells that make them potentially useful in medicine stem cells are undifferentiated cells a b embryo cells are stem cells c stem cells have retain the capacity to divide d can be used to produce cell cultures large number of identical cells e can be used to repair replace damaged lost cells tissue f stem cells are undifferentiated have not yet differentiated specialized g can differentiate specialize in different ways are pluripotent totipotent h can be used to form a variety of different tissues form organs i used in medical research j used in treatment of named disease k stem cells are pluripotent Discuss the advantages and disadvantages of the use of adult stem cells Advantages a adult stem cells can divide endlessly can differentiate b adult stem cells can be used to repair regenerate tissues c fewer ethical objections than with embryonic stem cells d adults can give informed consent for use of their stem cells e adult source is not killed source would not have grown into new human no death of embryos used to provide stem cells f no rejection problems patient s own cells used g less chance of cancer malignant tumor development than from embryonic stem cells h most tissues in adults contain some stem cells Disadvantages i difficult to obtain collect find in adult body very few available j some adult tissues contain few no stem cells k adult stem cells differentiate into fewer cell types than embryonic cells OWTTE Explain how multicellular organisms develop specialized tissues a only some genes are expressed in each cell type tissue b c example would be goblet cell tissues therefore develop differently become differentiated Explain how the properties of phospholipids help to maintain the structure of cell membranes a phospholipid consisting of head and two tails b head is glycerol and phosphate c tails are fatty acid chains d head hydrophilic and tails hydrophobic e hydrophilic molecules heads attracted to soluble in water f hydrophobic molecules tails not attracted to water but attracted to each other g properties of phospholipids leads to formation of double layer in water h stability in double layer because heads on outer edge are attracted to water and tails are attracted to each other in middle i phospholipid bilayer in fluid flexible state because of attraction of non polar tails to each other j fluidity allows membranes to change shape vesicles to form or fuse with membrane fluidity allows cells to divide k non polar amino acid side chains attracted to hydrophobic tails Describe how the structure of the membrane allows the formation of vesicles fluidity of membrane allows change of shape invagination formation of vesicles a b phospholipids can move phospholipid bilayer makes
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