BSC 2011 UNIT I STUDY GUIDE Fall 15 1 a For eukaryotes what is the function of i replication and where does it occur ii transcription and where does it occur and iii translation and where does it occur i Replication to duplicated DNA strands occurs in nucleus ii Transcription process in which DNA is converted into mRNA occurs in nucleus iii Translation process in which mRNA codons three nucleotide bases one codon one amino acid is decoded into a protein occurs in ribosome in the cytoplasm not in nucleus b What is a gene A gene is sequence of nucleotides that codes primarily for proteins Genes may also code for rRNA or tRNA c What is a chromosome A chromosome is a threadlike structure of nucleic acids and protein found in the nucleus of most living cells carrying genetic information in the form of genes d i What is meant by the genetic code The genetic code is the set of rules in which information encoded with genetic material whether DNA or mRNA sequences is translated into proteins by living cells The code is redundant multiple codons may code for the same amino acid due to third base wobble Genetic code is universal genes from one living organism may be capable of being expressed in another ex firefly gene expressed in a tobacco plant ii Distinguish between codons and anticodons Codon triplet of three mRNA bases codes for one amino acid Anticodon triplet sequence of tRNA bases each anticodon has a matching codon The corresponding amino acid codon attaches to the tRNA which then creates a growing polypeptide chain in the ribosome e i What is a mutation Mutation is a change in the genetic material of a cell ii What are the different types of genetic mutations Silent nucleotide is substituted for another nucleotide does not cause change to the amino acid originally coded due to redundancy in the genetic code does not change production function of protein Missense nucleotide is substituted for another nucleotide causes change to the amino acid originally coded different amino acid now may or may not change the production function of the protein Nonsense nucleotide indel insertion or deletion of nucleotide causes a frameshift mutation by changing how the codons are read throws off the triplets may cause an early or no stop signal no protein production iii Why are mutations important to cells organisms Mutations are important to cells organisms to create diversity A mutational change can have a huge ripple effect among many protein protein interactions f What is chromatin Distinguish between euchromatin and heterochromatin with respect to structure and function Chromatin is the material which makes up chromosomes composed of protein RNA and DNA it is in the nucleus Euchromatin loosely packaged DNA that can be transcribed polymerase can attach to DNA and be activated Heterochromatin tightly packaged DNA that cannot be transcribed genes are inactivated 2 a What is meant by gene expression Transcription DNA is transcribed into mRNA and translation mRNA condons are translated into a protein b What is meant by gene regulation The control of gene expression regulates transcription and translation c Why is gene regulation important necessary to cells organisms Genes tell when a cell should divide gene regulation differentiates cells turn on off enzymes that different cells need If this did not occur stomach intestinal cells would be where skin cells should be and we don t need our skin to have digestive enzymes 3 List the different classes of proteins describe their function in a cell organism and provide an example of each Defense ex antibodies Enzyme catalyze reactions ex salivary amylase DNA polymerase Hormone coordinate cell organelle activity ex insulin Motor contractile ex actin myosin Receptor respond to and bind to chemical stimuli ex olfactory receptors G proteins Storage amino acid reserves ex ovalbumin Structural support ex keratin collagen Transport move molecules ex hemoglobin 4 a Broadly and in general terms how and why do cells communicate Cells communicate through cell signaling Cell signaling can regulate the cells activity as well as communicate with other cells Cells receive signal molecules go through transduction chemical reactions that create a specific cellular response and the cell responds This response can be to turn a gene on off activate an enzyme or secrete a substance Examples of cell communication neurotransmitters secreted into synapses hormones secreted into the circulatory system to target specific cells tissues organs when to produce release digestive enzymes Cells signal and communicate with each other to guide embryonic development for a single fertilized egg cell zygote to develop into a multicellular embryo it requires this Cell division mitosis needs DNA replication cell differentiation specializes cells needs cell signaling and gene regulation morphogenesis body plan needs cell signaling gene regulation and cell movement b List and describe the three stages of cell signaling 1 Reception a signal molecule is received by a receptor molecule on the cell membrane or inside the cell 2 Transduction a stepwise series of chemical reactions initiated by an activated receptor molecule to bring about a specific cellular response 3 Response the end result of a specific signaling pathway cells reaction 5 a i Define genomic equivalence Different cell types have the identical genomes DNA but express different genes cell is told to turn on and off certain genes depending on what the cells function is ii All the somatic cells in an organism say the human body are genomically equivalent why What makes them different They are genomically equivalent because they have the same DNA The difference in cell type is due to the cell signaling and gene regulation b i What is meant by cell potency Cell potency is the ability of the cell to differentiate into other cell types ii What is a stem cell Stem cells are relatively undifferentiated cells that can be induced or made to differentiate iii Distinguish between and give an example of multipotent pluripotent and totipotent cells There are two types of embryonic stem cells stem cells from embryo totipotent and pluripotent Totipotent stem cells come from very early embryos and have the complete potential to go from cell to organism individual Example identical twins Pluripotent stem cells come from slightly older embryos are slightly differentiated some genes are turned off and can generate all embryonic cell types become any
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