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Chapter 12-1

What are the four bases? 1. Adenine 2. Thymine 3. Cytosine 4. Guanine
What does DNA do? It keeps code and contains instructions for the organism
What is sugar in DNA? Deoxyribose
What is the backbone of DNA made of? Sugar and phosphates
Purines 2 rings
Pyrimidines 1 ring
Chargaff's rules Adenine alsways bonds with thymine and guanine always bonds with cytosine.
Is DNA a double helix? Yes
What bonds between nitrogen bases and holds the two strgands together? Hydrogen
Describe the chromosome structure in prokaryotes -DNA is circular -DNA is single -Found in cytoplasm
Describe the chromosome structure of eukaryotes -DNA is in multiple -Chromome bundles -Found in necleus
What are eukaryotic chromosomes made of? DNA and proteins called histones
Nucleosome DNA and histone proteins formed in a bead-like structure
Base-pairing Adenine & thymine pair together and cytosine & guanine pair up
Replication forks Sites where strand separation and replication occur
3 replication steps 1. Enzymes "unzip" molecule by breaking down hydrogen bonds 2. DNA polymerase joins nucleotides using original strand as template and spell checks for errors 3. Copying happens in opposite directions along the two strands & in mulitiple places at once
RNA -Also made of nucleotides -Sugar is ribose instead of deoxyribose -Single stranded -Contains uracil instead of thymine
3 RNA help 1.Ribosomal - combines with proteins to form ribosomes 2. Transfer - matches m-RNA codon to add correct amion acids during protein synthesis 3. Messenger -carries code from DNA to ribosomes
RNA polymerase An enzyme that is responsible for creating RNA from a DNA template
How does RNA polymerase know where a gene starts and stops? -(Promoters) enzyme binds to places with certain DNA sequences -Promoters tell RNA polymerase where to start -Signals at the end of the gene code cause transcript to stop
Why spend energy making a large RNA and then throw parts away? The same gene can be used in different ways
Where does transcription and processing take place? In the nucleus
Where does translation take place? On ribosomes in cytoplasm
Codons Sequence of three nucleotides that together form a unit of genetic code
How many possible codons are there? 64
How much amino acid does tRNA carry? Only 1 kind
Replication RNA - DNA
Transcription DNA - RNA
Translation RNA - Protein
Central dogma of biology Basic framework for how genetic information flows (DNA - RNA - Protein)
Mutations Changes in the genetic material
When do mutations happen? -Mistakes in copping their own DNA -Radiation -Chemicals in the environment
Gene mutations Mutations that produce changes in a single gene
Chromosomal mutations Mutations that produce changes in whole chromosomes
Point mutation Mutations involving one or a few nucleotides
What are the 3 types of point mutation? 1. Substitutions 2. Deletions 3. Insertions
Substitution Changes one base for another
Deletion Piece of DNA code for one gene is lost
Insertion Piece of DNA is copied too many times
Frame shift mutations Change multiple bases in code
Are mutations at the beginging of the gene damage more or less of the code? More of the code
Chromosomal mutations Mutations invlolving changes in the number or structure of whole chromosomes
What are the types of chromosomal mutations? -Deletions -Duplications -Inversions -Translocations
Duplication Piece of DNA is copied too many times
Inversion Segment flips and reads
Translocation Segment breaks off and joins a different non-homologous chromosome
Facts about mutations -Most mutations are neutral, they have little or no effect on gene function -Mutations that cause defective proteins are usually harmful -Harmful mutations are associated with many genetic disorders and can cause cancer
What are mutations a source of? Genetic variablility and beneficial
How are mutiations helpful? They provide variation in population for natural selection to act upon
Polyploidy Condition in which an organism has extra sets of chromosomes
Regulatory sites Control whether a gene is ON of OFF
Operon Group of genes that operate together
Repressor molecule It sits on a regulatory site next to the promoter called the operator
TATA box DNA sequence that indicates where a genetic sequence can be read and decoded
How do cells differentiate? By turning different genes on and off
Hox genes -These genes control the organization of the developing embryo -Tell parts where to grow / when
How do you know when organisms share a common ancestor? They similarites betwwen Hox gene sequences and ability of these genes to trade places, and still function in different species
Created by: kieren1
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