BIO_SC 1010: Chromosomes
27 Cards in this Set
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Chromosomes
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one long DNA molecule wrapped around a series of proteins found in cells
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Four Types of Nucleotides and what bases they bond with
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A= Adenine :: T= Thymine
--> C= Cytosine :: G= Guanine
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Purpose of DNA
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-instructs cells to make proteins.
- made out of a long strand of amino acids and the structure and function of protein is determined by the order of its amino acids - the order of amino acids is determined by the order in which ATC & G occur on the chromosome
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Gene
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a segment of DNA specifying the sequence of amino acids in a single protein
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Mutation
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a change in the sequence of bases in DNA
-cause frame shifts in reading the codons -all codons 'downstream' are affected -protein is likely to be dysfunctional
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Point Mutation
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one base changes to another
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Insertion or deletion
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One (or more) bases is inserted/removed
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Gene Duplication
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- large chunk of DNA is duplicated within the strand
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What causes mutations?
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-high energy radiation (x rays/UV light)
- chemicals that resemble bases - mutations that result in protein structure may be harmful, neutral or beneficial
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How do cells protect themselves from mutations?
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-repair enzymes
-redundancy of the code -some codons code for the same amino acids -only 20 amino acids q
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Cell Division:
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1.) Mitosis- cellular reproduction
2.) Meiosis
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Mitosis
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-important for growth, repair
-ex: fetus -reproduction of single celled organism Function: produce 2 new cells from 1 old cells, (daughter cells) genetically identical to the mother cell
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Meiosis
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-production of sperm and egg cells
-gametes= sperm/eggs -reduces the number of chromosomes in the gametes by half -occurs in the ovaries/testies
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Homologous chromosomes
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-2 chromosomes similar in structure, 1 mom and 1 dad
-contain the same genes in the same location on the chromosomes -each gamete contains a unique mixture of your DNA
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Haploid
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-containing only 1 (gametes) chromosome from each homogolous pair
-sperm cell -different lengths
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Diploid
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containing homologous pairs of chromosomes (all others)
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Gene expression
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-Genes are not active all the time
-different shapes/functions -expressed= transcribed into mRNA and translated into protein
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How is gene expression regulated?
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-1.) turning genes on and off based on the developmental stage of the organism and the type of tissue that the cell is a part of (activator proteins: bind to genes, and then turn them on)
-on: transcription -off: no transcription -2.) varying the rate of transcription or translation
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External environmental cues
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food, sunlight, temperature, behavior
*
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Regulatory Gene
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-a gene that codes for an activator protein
-control expression of other genes by turning them off/on -one regulatory gene may control the expression of many other genes -important during early development
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Cancer
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Uncontrolled cell division or mitosis when a regulatory gene that controls cell division is turned on by mistake, the cell will divide without control
- tumor is malignant
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Oncogene
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a growth regulatory gene that has malfunctioned stimulating uncontrolled cell division, like an accelerator in a car
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Tumor
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-any clump of cells, produced through rapid cell division can be either: benign or malignant (spread)
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Suppressor Gene
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suppressor gene: a gene that inhibits cell division. Mutations prevent inhibition, like brakes
-Mutations: loss of brakes - most cancers require multiple mutations
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Characteristics of Cancer
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rapid cell division and loss of cell differentiation (specialization)
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Metastasis
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-cancer spreads to other parts of the body and changes in cell shape
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What causes Cancer?
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carcinogens, high energy radiations, chemicals that mimic bases, viruses that can insert oncogenes into the DNA of a cell, hormones, certain foods?, tobacco
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Study Guide: Final Exam