BSC 2011 UNIT I STUDY GUIDE The purpose of this study guide is to encourage you to review your notes and text material and to integrate numerous facts and terms into broad but meaningful concepts Please try and work on your own at first but don t hesitate to ask for assistance from either me or your TA We will randomly select a question or part thereof to use on your Unit I exam Dr Spears 1 a Compare and contrast i DNA ii mRNA and iii protein a DNA mRNA and protein are all part of the central Dogma which is the flow of genetic information a DNA Genetic information is stored in the order or sequence of nucleotides Nucleotides code for a polypeptide a protein or a RNA molecule tRNA rRNA A genome is all of an organism s genetic material in a cell RNA The intermediary molecule in the flow of genetic information 3 major types of RNA mRNA messenger tRNA transfer rRNA ribosomal Proteins Made of strands of amino acids Types and functions enzymes catalyze reactions structural support transport other molecules hormones coordinate cell activities receptors respond to and bind chemical stimuli defense motor protein storage of amino acids In short DNA is genetic information stored in the order or sequence of nucleotides mRNA is the template for protein synthesis A protein is any of a large group of nitrogenous organic compounds that are essential constituents of living cells b 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 ii iii Replication occurs in DNA in the nucleus and makes copies of DNA Transcription occurs in the nucleus and is the organic process whereby the DNA sequence in a gene is copied into mRNA Translation is the process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosome in the cytoplasm c What is the role of i ribosomes and ii tRNA Ribosomes are composed of RNA They are also the sites of protein synthesis where RNA is translated into protein Two subunits of RNA are used to make the proteins tRNA is used to carry amino acids in the cytoplasm to help build the polypeptide d i What is meant by the genetic code ii Distinguish between codons and anticodons i The genetic code is the ordering of nucleotides in DNA molecules that carries the genetic information in living cells A codon triplet of 3 mRNA bases codes for one amino acid Multiple codons can code for the same amino acid ii Codons are the triplets of mRNA bases and an anticodon is a group of three bases on a tRNA molecule that are complementary to an mRNA codon e i What is a mutation ii What are the different types of genetic mutations iii why are mutations important to cells organisms i ii A mutation is a change in the genetic material of a cell Different types of genetic mutations a point mutations a change in just one nucleotide b substitutions exchange one base for another may or may not change the amino acid insertions or deletions indels extra base pair inserted or a section may be lost c d i causes missense mutation frameshift alters codon reading frame i may cause a nonsense mutation with an early or no stop signal and NO PROTEIN iii Genetic mutations are essential to evolution and help species develop new useful characteristics and traits f What is a gene g What is a chromosome A discrete unit of hereditary information on part of a chromosome consisting of a specific sequence of 100 s or 1000 s of nucleotides coding for a polypeptide or RNA molecule Structural units composed of chromatin 1 chromosome 1 long double stranded helical DNA molecule and its bound proteins h What is chromatin Distinguish between euchromatin and heterochromatin with respect to structure and function Chromatin is DNA and the various proteins that bind to DNA Euchromatin a b DNA wraps around nucleosomes 8 of the 5 types of histone proteins c actively transcribed packed DNA and proteins loosely Heterochromatin a b c only found in eukaryotes involved in gene regulation and chromosome structure tightly packed DNA and proteins genetically inactive not being transcribed 2 a What is meant by gene expression The synthesis of mRNA using DNA as a template the flow of genetic info What is meant by gene regulation At what level is gene expression generally controlled Why is gene regulation important necessary to cells organisms Gene regulation is the control of gene expression regulating transcription and translation Genes are generally controlled at the transcriptional control level It is important because different types of cells need to turn on different genes so that they are expressed This will alter what proteins are made by different cells Some genes have constitutive expression meaning they re always on and some are expressed or repressed as needed in facultative expression Since all cells have the same genes it takes regulation of the genes to turn on the right ones needed for the cell b What is the role of each of the following with respect to gene regulation i e in what way does each affect gene regulation i transcription factors ii control elements i Transcription factors are regulatory proteins that respond to a signal bind to specific DNA sequences near a gene regulation of gene expression on a gene level and is the most prevalent form of gene expression They are regulatory proteins that respond to a signal and bind to specific DNA sequences near a gene in transcription a TFs facilitate binding of RNA polymerase to the promoter of a gene forming a transcription initiation complex ii Control elements are DNA sequences upstream of a gene where you can find transcription factors Transcription factors bind to the control elements to regulate genes at the initiation of transcription a TFs bind to control elements regulate genes at the initiation of transcription they turn on turn off modulate the amount of transcription by influencing b binding of RNA polymerase the particular TFs in a cell determine which genes are expressed in different cell types c 3 List the different types of proteins describe their function in a cell organism and provide an example of each i enzymes catalyze reactions e g DNA polymerase structural support e g keratin collagen transport other molecules e g hemoglobin hormones coordinate cell org activities e g insulin receptors respond to bind to chemical stimuli e g olfactory receptors G proteins defense e g antibodies contractile motor proteins e
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