DNA and RNA http faculty uca edujohncmbi 1440

DNA and RNA http: //faculty. uca. edu/~johnc/mbi 1440. htm Chapter 12 -1 Slide show by Kelly Riedell/Brookings Biology http: //www. wappingersschools. org/RCK/staff/teacherhp/johnson/visualvocab/m. RNA. gif

DNA is a DOUBLE HELIX http: //www. time. com/time 100/scientist/profile/watsoncrick. html http: //en. wikipedia. org/wiki/Rosalind_Franklin X-ray experiments by Rosalind Franklin led James Watson and Francis Crick to the discovery of the structure of DNA in 1953

Section 12 -1 Figure 12– 7 Structure of DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

NUCLEIC ACIDS are built from subunits called NUCLEOTIDES __________ Image by: Riedell SUGAR in DNA is ________ deoxyribose

NITROGEN BASES in DNA _______= A ADENINE _______ =G GUANINE _______ CYTOSINE = C _______ THYMINE = T No URACIL

DEOXYRIBONUCLEIC ACID DOUBLE _______ STRANDED Image from: http: //www. tokyo-med. ac. jp/genet/picts/dna. jpg Backbone (sides of ladder) made of PHOSPHATES _______ and sugars _______

Nitrogen bases =“Steps of ladder” A Phosphate group G Deoxyribose sugar C T Purines

CHARGAFF’S RULES A = T G = C _________ At time no one knew why… now we know its because Adenine always bonds THYMINE across with______ Guanine always bonds CYTOSINE across with ______ Image from: http: //evolution. berkeley. edu/evosite/evo 101/images/dna_bases. gif

DOUBLE HELIX Hydrogen _______ bonds between nitrogen bases hold the two strands together. Image from: http: //evolution. berkeley. edu/evosite/evo 101/images/dna_bases. gif

Deoxyribonucleic acid (DNA) Nitrogen bases are attached to sugar at Carbon #1 Phosphates are attached to sugar at Carbon #5 So each strand has a 3’ and 5’ end http: //staff. um. edu. mt/acus 1/3 Molgen. htm

Strands run in opposite directions ANTI-PARALLEL = __________ Image from: http: //evolution. berkeley. edu/evosite/evo 101/images/dna_bases. gif

CHROMOSOMES & DNA REPLICATION 12 -2

Chromosome Structure in Prokaryotes Approximately 5 million base pairs 3, 000 genes Chromosome E. coli bacterium Bases on the chromosome DNA molecule in bacteria is: SINGLE _______ CIRCULAR _______ CYTOPLASM (NO nucleus) Found in _____ © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

DNA in EUKARYOTES is packaged into chromosomes http: //www. paternityexperts. com/images/DNA-of-life. jpg Humans have approximately 3 billion base pairs (1 m long) 60, 000 to 100, 000 genes If the diameter of the DNA (2 nanometers) was as wide as a fishing line (0. 5 millimeters) it might stretch as far as 21. 2 km (or 13. 6 miles) in length which would all have to be packed into a nucleus, the equivalent size of 25 cm in diameter. That is some packaging!

THINK ABOUT IT How could you get this piece of string into the container? http: //www. artzooks. com/files/3966/AZ 533823_320. jpg http: //www. mivaroo. com/sites/toyconnection. com/

Chromosome Structure of Eukaryotes © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved Chromosome Nucleosome DNA double helix Coils Supercoils DNA is: multiple in _____ chromosome bundles ______ Found in _____ nucleus Histones

Chromosome Structure of Eukaryotes © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved Eukaryotic chromosomes are Nucleosome made of PROTEINS DNA _____ & _____ called ______ HISTONES Together the DNA & histone proteins forms a bead-like NUCLEOSOME structure called a _______ Histones DNA double helix

© Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved Chromosome Structure of Eukaryotes Nucleosome Chromosome DNA double helix Coils Supercoils Histones Nucleosomes pack together to form thick coiled fibers. When cell is NOT dividing, these fibers are spread out in nucleus as CHROMATIN (Allows reading of code) ______.

Chromosome Structure of Eukaryotes © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved Chromosome Nucleosome DNA double helix Coils Supercoils Histones When cell gets ready to divide, the fibers pack even more tightly to form chromosomes ______. -Easier to move DNA during mitosis

Image from: http: //evolution. berkeley. edu/evosite/evo 101/images/dna_bases. gif HOW IS DNA COPIED? The structure of DNA explains how it can be copied. Each strand has all the info needed to construct matching the _____other half. If strands are separated, base-pairing rules allow _______ you to fill in the complementary bases.

Figure 12– 11 DNA Replication Section 12 -2 New strand Original strand DNA polymerase Growth Replication fork Nitrogenous bases Replication fork New strand Original strand Sites where strand separation and replication forks replication occur are called _______

REPLICATION STEPS 1. Enzymes “unzip” molecule by breaking ________ Hydrogen bonds that hold the strands together and unwind it. DNA polymerase joins nucleotides 2. ________ using original strand as template and spell checks _______for errors. opposite directions 3. Copying happens in ____ along the two strands & in _____ multiple places at once.

REPLICATION ANIMATION See a video clip about DNA REPLICATION (12 B)

ACTIVITY • BE A DNA MOLECULE

RNA and PROTEIN SYNTHESIS 12 -3 © Pearson Education Inc, publishing as Pearson Prentice

RNA- the Other Nucleic Acid NUCLEOTIDES Also made of ______ RIBOSE instead Sugar is _______ of deoxyribose. SINGLE stranded RNA is _____ URACIL Contains _____ instead of thymine. http: //images 2. clinicaltools. com/images/gene/dna_versus_rna_reversed. jpg

3 KINDS OF RNA HELP WITH INFO TRANSFER FOR PROTEIN SYNTHESIS RIBOSOMAL _________RNA (r. RNA) Combines with proteins to form ribosomes TRANSFER _________RNA (t. RNA) Matches m-RNA codon to add correct amino acids during protein synthesis _________RNA (m. RNA) MESSENGER carries code from DNA to ribosomes r. RNA and t-RNA images from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved m. RNA image from http: //wps. prenhall. com/wps/media/tmp/labeling/1140654_dyn. gif

Section 12 -3 Figure 12– 14 Transcription Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase RNA DNA RNA POLYMERASE Enzyme called ___________ separates strands, then uses one strand as a template to assemble an RNA copy.

How does RNA POLYMERASE know where a gene starts and stops? Enzyme binds to places with specific DNA PROMOTERS sequences called ________. RNA POLYMERASE PROMOTERS tell _________ where to start. Signals at the end of the gene code cause transcription to _____ stop. http: //images 2. clinicaltools. com/images/gene/dna_versus_rna_reversed. jpg

Video 3 Transcription animation See another transcription animation See a video clip about TRANSCRIPTION (12 C)

ACTIVITY • TRANSCRIPTION of DNA

NON CODING DNA • • • More than 90% of human DNA “JUNK” DNA Originally called _______ REGULATION- Turn genes on/off TELOMERES - protective ends INTRONS ______pieces edited out of message PSEUDOGENES - non functional genes due to mutations • VIRAL ELEMENTS - Leftovers from viral infections TRANSPOSONS • ________

m. RNA’s require EDITING before use Image by Riedell

EX: antibody production different Immune system needs to be able to make a huge number of different antibodies to match new and different invaders http: //www. sciencegeek. net/Biology/review/graphics/Unit 8/Antibody. gif http: //1. bp. blogspot. com/_bje. C 1 Cy. B 28 w/TOijgcet. Vj. I/AAAAAvo/0 h. PZmygf. SZo/s 1600/colourful_cartoon_germs_bumper_sticker-p 128396365988627252 trl 0_400. jpg

• • • TRANSPOSONS “Jumping” ______ genes Can move from one place to another 1 st described by Barbara Mc. Clintock in corn Environmental stress increases jumping Can move genes to new site Increase mutation rate http: //www. nature. com/nature/journal/v 443/n 7111/images/443521 a-i 1. 0. jpg http: //www. osti. gov/accomplishments/images/mcclintock_05. jpg

IT’S NOT “JUNK”! • Allows same gene to be used in different ways in different kinds of cells. • Differences in organisms are more about differences in regulation than in genes themselves • Role in evolution? Small changes in genes can have a big effect Mutations give natural selection new choices

MASTER PLAN DNA stays safe in nucleus © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved TRANSCRIPTION (DNA→ RNA) & PROCESSING takes place in nucleus TRANSLATION (RNA→ proteins) takes place on ribosomes in cytoplasm “Blueprints” of master plan are carried to building site http: //www. home-improvement-resource. com/images/architect. jpg

HOW CAN JUST 4 BASES GIVE DIRECTIONS TO MAKE 20 AMINO ACIDS? CODON Message is read in groups of 3 = _____ UCGCACGGU UCG-CAC-GGU Serine - Histidine - Glycine Codons represent different amino acids

The m-RNA Code Section 12 -3 64 possible codons Some amino acids have more than one codon. AUG START= _______ STOP 3 codons for _____

ANTICODON ______ on t. RNA EACH t. RNA carries only one kind of amino acid _______ matches up with CODON ____ on m. RNA Images modified from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

Section 12 -3 Figure 12– 18 Translation

Section 12 -3 Figure 12– 18 Translation (continued)

Video 4 SEE ANOTHER Translation Animation See a video clip about PROTEIN SYNTHESIS (12 D) TRANSLATION VIDEO (Choose Large video)

REPLICATION DNA → DNA ______ TRANSCRIPTION DNA → RNA ______ RNA→ Protein TRANSLATION ______

Mendel/flower images from: http: //www. emc. maricopa. edu/faculty/farabee/BIOBK/Bio. Book. TOC. html Blood cell by Riedell GENES & PROTEINS Proteins are the connection between the gene code in the DNA and how that gene is expressed. A gene that codes for an enzyme (protein) to make a pigment can control the color of a flower. A gene that codes for an enzyme (protein) adds carbohydrates to glycoproteins to produce your blood type. Enzymes catalyze and regulate chemical reactions so proteins build and operate all cell components.

CENTRAL DOGMA OF BIOLOGY How is information passed? DNA → ______ RNA PROTEIN _____ → ____ Then the protein “DOES SOMETHING” that shows up as a ____ trait

MUTATIONS 12 -4

REMEMBER! MUTATIONS ________ are changes in the genetic material. Mutations can happen when cells make mistakes _______ in copying their own DNA radiation or be caused by ________ or chemicals in the enviroment. ______

KINDS OF MUTATIONS Mutations that produce changes in a single GENE MUTATIONS gene = ___________ Mutations that produce changes in whole chromosomes = ___________ CHROMOSOMAL MUTATIONS

GENE MUTATIONS One or a few Mutations involving ________ = _________ nucleotides Point mutation because they occur at a single point in the DNA sequence. TYPES OF POINT MUTATIONS: ___________ substitutions deletions ___________ insertions ___________

SUBSTITUTION Changes one base for another ATTCGAGCT ATTCTAGCT

SICKLE CELL ANEMIA CAUSE: (autosomal recessive) A changed to T (glu to val) gene on chromosome #11 that codes for part of hemoglobin protein (carries oxygen in blood)

DELETION ____________________ Piece of DNA code for one gene is lost Image from: http: //www. biology-online. org/2/8_mutations. htm

Duchenne Muscular Dystrophy CAUSE: (X linked recessive) DELETION in gene that codes for a muscle protein

INSERTION Extra piece of DNA is added Image from: http: //www. biology-online. org/2/8_mutations. htm

GENE MUTATIONS Substitutions usually affect no more than a Amino acid but deletions and single ______, insertions can have a more dramatic effect. IMAGE FROM BIOLOGY by Miller and Levine; Prentice Hall Publishing© 2006

FRAME SHIFT MUTATIONS Change multiple bases in code thefatcatatetherat the fat cat ate the rat __________ INSERTION thefatcatateatetherat the fat cat ate ate the rat DELETION thefatcatatetherat the fat ata tet her at

FRAME SHIFTS Frame shift mutations change every Amino acid ______ in the ______ protein that follows the shift. Frame shifts can alter a protein so function much it is unable to _______

CHROMOSOMAL MUTATIONS Mutations involving changes in the Number structure _______ or _______ of whole chromosomes TYPES OF CHROMOSOMAL MUTATIONS: deletions ___________ See a Video duplications ___________ inversions ___________ translocations ___________ (deletions & duplications See a Video (inversions & translocations

DELETION Piece of chromosome is lost ____________________ Image from: http: //www. biology-online. org/2/8_mutations. htm

DUPLICATION Piece of DNA is copied too many times ________________________ Image from: http: //www. biology-online. org/2/8_mutations. htm

HUNTINGTON’S • Degenerative brain disorder • Symptoms appear age 30 -40 • Lose ability to walk, think, talk, reason • Cause = ADDITION of extra CAG repeats

INVERSION Segment flips and reads backwards Image from: http: //www. biology-online. org/2/8_mutations. htm

TRANSLOCATION Segment breaks off and joins a different non-homologous chromosome Image from: http: //www. biology-online. org/2/8_mutations. htm

MUTATIONS neutral Most mutations are ______ meaning they have little or no effect on gene ______. function defective proteins Mutations that cause ________ HARMFUL are usually ______ Harmful mutations are associated with many genetic disorders and can cause ________ cancer

MUTATIONS Mutations are also a source of Genetic variability _________ and can be beneficial _______ Can help an organism _________ Survive and reproduce variation Provide _____ in population natural selection for ______ to act upon MORE ON THIS 2 nd SEMESTER!

POLYPLOIDY Condition in which an organism has extra sets of chromosomes POLYPLOIDY = ________ LETHAL _____ in humans, but beneficial in some ______. plants 3 N or tetraploid (___) 4 N Triploid (___) plants are often ________ larger and stronger than diploid plants.

GENE REGULATION 12 -5 http: //www. awesomebackgrounds. com/s-energy-and-power. htm

$Only a fraction of genes in a cell are expressed (made into RNA) at$

Only a fraction of genes in a cell are expressed (made into RNA) at any given time. How does the cell decide which will be turned on and which will stay “silent”? PROMOTER You already know about _______ regions that show RNA polymerase where to start. REGULATORY SITES that There are other ___________ control whether a gene is ON or OFF.

Typical Gene Structure Section 12 -5 Regulatory sites Promoter (RNA polymerase binding site) Start transcription DNA strand Stop transcription

E. Coli lac operon See a MOVIE choose animation/narrated Group of genes that operate together are OPERON called an ________ Genes code for enzymes needed to digest lactose sugar. Only needed if glucose is not available http: //www. life. uiuc. edu/bio 100/lectures/s 97 lects/16 Gene. Control/lac_operon_ind. GIF

Most of time glucose is available so OFF by a lac operon is turned _____ REPRESSOR ______ molecule that sits on a regulatory site next to the promoter OPERATOR called the ______

What if there’s NO GLUCOSE? Cells need to get rid of the repressor ON and turn _____the lac genes to digest lactose instead. The presence of lactose causes a change in the ______ REPRESSOR molecule so so it can’t bind the operator site. Image modified from: http: //www. life. uiuc. edu/bio 100/lectures/s 97 lects/16 Gene. Control

Cells turn genes ON & OFF as needed Many genes are regulated by REPRESSOR _______ proteins that keep them turned off until needed. Others use proteins that speed up transcription ________ or affect protein synthesis __________

EUKARYOTES are more COMPLEX Additional regulatory sequences: ENHANCER regions 1. ______ upstream from promoters bind many different regulatory proteins TATA box 2. _____ (TATATA or TATAAA) helps position RNA POLYMERASE Image by Riedell

DEVELOPMENT & DIFFERENTIATION Gene regulation is also important in shaping way organisms develop How does a zygote become a multi-cellular organism? How does it know what kind of cell to be?

DEVELOPMENT & DIFFERENTIATION Cells DIFFERENTIATE ________ by turning different genes on and off. http: //www. ncu. edu. tw/~ls/graph/faculty_pictures/whole_time/SLC_lab-1. jpg BUT… How does a cell know where it is in the body? and what genes it should turn on? and when?

In the 1980 s, researchers discovered a series of genes in fruit flies called Hox genes ______ These genes control the organization of the developing embryo and tell parts where to grow and when. Mutations to Hox genes can cause a leg to grow where an antenna should sprout. http: //evolution. berkeley. edu/evosite/history/hox. shtml

Since that time, HOX genes with almost identical sequences have been found in a variety of organisms including HUMANS ______ © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

HOX GENES Similar genes controlling the eyes of insects and our own eyes have also been discovered. Our version of the gene can be inserted in a fly and still trigger the building of an insect eye! http: //evolution. berkeley. edu/evosite/history/hox. shtml

SO WHAT? The similarities between HOX gene sequences in very different organisms and the ability of these genes to trade places and still function in different species suggests that these organisms share a common ancestor _____________