BSC 2011 UNIT I STUDY GUIDE Fall 14 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 The questions are arranged in the order we cover topics in class TEST YOURSELF by trying to answer the questions on your own at first this tells you what you know and what you don t know then fill in the gaps with notes your text and don t hesitate to ask for assistance from either me or your TA Dr T 1 a For eukaryotes what is the function of i replication and where does it occur Replication is DNA copied into DNA occurs in the nucleus ii transcription and where does it occur Transcription is the process of taking copied DNA and making mRNA occurs in nucleus iii translation and where does it occur Translation is when mRNA in the nucleus is decoded into a specific protein at a ribosome in the cytoplasm mRNA codons are translated into an amino acid in a protein occurs in cytoplasm b What is a gene A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA c What is a chromosome A cellular structure consisting of one DNA molecule and associated protein molecules typically located in the nucleus d i What is meant by the genetic code a codon triplet of 3 mRNA bases codes for 1 amino acid the code is redundant and multiple codons may code for the same amino acid due to third base wobble it is also virtually universal indicating an ancient origin of the common ancestor of modern life forms ii Distinguish between codons and anticodons codons are a 3 nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal and is the basic unit of the genetic code anticodons are a nucleotide triplet at one end of a tRNA molecule that base pairs with a particular complementary codon on an mRNA molecule tldr codons are located on tRNA mRNA and anticodons are located on AUU AUU codon UAA anticodon e i What is a mutation A change in the genetic material of a cell and can be large scale or small scale they may or may not alter a codon and the amino acid for which it codes examples include nucleotide substitutions and nucleotide insertions or deletions indels ii What are the different types of genetic mutations Point mutations are a change in just one nucleotide in a gene Silent mutations is a nucleotide nt substitution mutation in which the third base is substituted due to third base wobble the amino acid does not change and the mutation is silent Missense mutations are also nt substitutions however they cause the amino acid to change since either the first or second base is substituted Nonsense mutations are nt indels that alter the entire reading frame they cause either an early or no stop signal and no protein iii Why are mutations important to cells organisms Mutations can have a huge ripple affect and may affect many protein protein interactions However they cause genetic diversity and Anticodons are the opposite to the codons ex evolution to occur however mutations can also cause proteins to either not occur or be damaged proteins are essential to humans Examples in question 3 Additionally if a disaster happened most likely all organisms would not die because some of them are different are may survive f What is chromatin Distinguish between euchromatin and heterochromatin with respect to structure and function Chromatin is genetic material composed of DNA and proteins that condense to form chromosomes during eukaryotic division Euchromatin is loosely packaged DNA that can be transcribed Heterochromatin is tightly packaged DNA that is not transcribed 2 a What is meant by gene expression Transcription and translation 2 types constitutive genes that are always on and facultative genes are expressed or repressed as needed b What is meant by gene regulation The control of gene expression c Why is gene regulation important necessary to cells organisms Gene regulation gone wrong can cause cancer and disease Cell determination in which cells become specialized skin cells muscle cells nerve cells etc relies on cell signaling and gene regulation to make cell specific proteins Morphogenesis sets up body plan also relies on gene regulation 3 List the different classes of proteins describe their function in a cell organism and provide an example of each Enzymes catalyze reactions ex DNA polymerase structural proteins provide support ex Keratin collagen transport proteins transport other molecules ex Hemoglobin hormone proteins coordinate cell organize activities ex Insulin receptor proteins respond to and bind to chemical stimuli ex Olfactory receptors G proteins defense proteins provide defense for the body ex Antibodies motor contractile proteins help with moving ex Actin myosin storage proteins store amino acid reserves ex Olvabumin 4 a Broadly and in general terms how and why do cells communicate Cells use signaling mechanisms to regulate cell activities ex Turning genes on off changing cell shape when cells should divide or die and to communicate with other cells ex Neurotransmitters secreted into synapses hormones secreted into circulatory system to target certain cells tissues organs when to produce release digestive enzymes when to stop eating For a zygote to eventually developi into a multicellular embryo and then an adult cells need to signal and communicate b List and describe the three stages of cell signaling 1 Reception a signal molecule is received by a receptor molecule on a cell membrane or inside a 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 and activation of a cellular response such as turning a gene on or off 5 a i Define genomic equivalence All the different cell types in an organism have identical genomes same DNA but they express different genes evidence is found in totipotency the potential of a cell to differentiate into an entire organism because no genes are irreversibly turned off ii All the somatic cells in an organism say the human body are genomically equivalent why What makes them different When a cell divides it makes the same DNA Due to determination a cell can differentiate into a particular cell type by expressing a unique set of genes b What is meant by cell potency cell potency refers to a cell s ability to differentiate into another type of cell
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