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DNA and RNA DNA was the first three-dimensional Xerox machine – Kenneth Ewart Boulding.

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Presentation on theme: "DNA and RNA DNA was the first three-dimensional Xerox machine – Kenneth Ewart Boulding."— Presentation transcript:

1 DNA and RNA DNA was the first three-dimensional Xerox machine – Kenneth Ewart Boulding

2 Essential Standards Bio.3.1 Explain how traits are determined by the structure and function of DNA. – Bio Explain the double-stranded, complementary nature of DNA as related to its function in the cell. Bio Explain how DNA and RNA code for proteins and determine traits. Bio Explain how mutations in DNA that result from interactions with the environment (i.e. radiation and chemicals) or new combinations in existing genes lead to changes in function and phenotype. Bio.3.2 Understand how the environment, and/or the interaction of alleles, influences the expression of genetic traits. – Bio Explain the role of meiosis in sexual reproduction and genetic variation. Bio Predict offspring ratios based on a variety of inheritance patterns (including dominance, co-dominance, incomplete dominance, multiple alleles, and sex-linked traits). Bio Explain how the environment can influence the expression of genetic traits. Bio.3.3 Understand the application of DNA technology. – Bio Interpret how DNA is used for comparison and identification of organisms. Bio Summarize how transgenic organisms are engineered to benefit society. Bio Evaluate some of the ethical issues surrounding the use of DNA technology (including cloning, genetically modified organisms, stem cell research, and Human Genome Project).

3 STRUCTURE AND FUNCTION OF DNA We have come a long way on that old molecule [DNA].

4 Brief Review: What type of macromolecule is DNA or RNA? What monomer makes up DNA? What are the components of this monomer? What organelle houses DNA? What is the division of this organelle called? What part of the cell cycle is DNA replicated in? Nucleic acid Nucleotides sugar, phosphate, nitrogenous base Nucleus Mitosis Interphase, S phase

5 How was DNA discovered? James Watson and Francis Crick won the race to find the structure of DNA, and a Nobel prize in 1962 Maurice Wilkins was later also added to the prize list for his contributions

6 How was DNA discovered? cont’d Wilkins was also working on the problem Rosalind Franklin worked in Wilkins lab taking X-ray diffraction pictures of DNA Her pictures supported the DNA structure She was never given credit as she died before Wilkins name was added due to X-ray exposure

7 How is DNA structured? DNA is double stranded Backbone made of alternating phosphates and deoxyribose sugars Contains 4 bases (“rungs of the ladder”) – Adenine (A) – Thymine (T) – Cytosine (C) – Guanine (G) Looks like a twisted ladder

8 How is DNA studied? Genetics –branch of biology that studies heredity Heredity – how traits are passed from parent to offspring Traits – characteristics of an organism – ex. body shape, cell shape, proteins produced – nucleic acids contain information that determine traits made of?

9 What are nucleic acids? Macromolecules made of nucleotides nucleotides are made up of a sugar backbone, a phosphate, and a nitrogenous base cells contain 2 types – DNA (deoxyribonucleic acid) – RNA (ribonucleic acid) Both contain 5 carbon sugars arranged in a ring

10 What is the function of DNA? Carries genetic information instructions for cellular activity and making necessary proteins – What are the different structures of proteins? – How do those structures interact?

11 Where is DNA? Where do you find DNA in prokarotes? What are small circular pieces of DNA in prokaryotes called? Where do you find DNA in eukaryotes? In eukaryotes, DNA is coiled into structures called chromosomes – What is DNA normally when it is uncoiled? chromatin

12 How is DNA structured? made of linked nucleotides – nucleotides are all the same except with a different nitrogenous base A C T G shaped like a twisted ladder = double helix – strands of alternating deoxyribose sugars and phosphates – rungs are one of four bases


14 How do the bases of DNA work? Chargaff’s rule: – A always pairs with T – C always pairs with G These are called complementary base pairs Held together by weak hydrogen bonds sequence of bases stores genetic information


16 How does DNA determine traits? traits are based on proteins produced in an organism proteins are not made directly by DNA information is copied from DNA to an RNA molecule (transcription) RNA carries information to ribosomes (translation) – What do these make? – What to they make proteins from?

17 Why is DNA replicated? Cells are alive so what must they do? During the cell cycle, when is DNA replicated? DNA is replicated so that each daughter cell has identical DNA to the parent cell

18 How is DNA replicated? Step 1: helicase enzymes break H bonds and unwinds DNA down the middle – 2 going in opposite directions Step 2: DNA polymerase enzymes from cytoplasm join complementary base pairs to make a matching strand synthesized from 5’ to 3’

19 What is the result of DNA replication? 2 strands of identical DNA each strand is half old DNA and half new DNA – semiconservative process Build a DNA Molecule

20 Assignment! DNA replication worksheet Use your notes to help you with the information… IT IS ALL HERE

21 What are chromosomes? chromosomes – are structures of containing genetic information passed down from parent to offspring DNA is a long molecule, nucleus of a human contains over a meter of DNA! – coiled to save space so DNA can fit in the nucleus

22 How are chromosomes and genes related? Each specie has a specific number of chromosomes segments of chromosomes (or DNA) that code for proteins are called genes – many genes on 1 chromosome organisms have many more inherited genes that chromosomes

23 How is DNA compared between species? Genetic information varies between species DNA of all organisms have some things in common The more common things they share the more closely related they are Similarity determined by how many genes are shared AND how alike those genes are Smaller variations are also present among members of the same species

24 Assignment! DNA extraction You will need: – strawberry – ziploc bag – DNA extraction buffer – cheesecloth – funnel – test tube – stirring rod – alcohol


26 Brief Review What are traits determined by? What are proteins made of? Where do instructions to make proteins come from? What type of macromolecule is RNA? So what are the monomers of RNA? Proteins! Amino Acids! DNA! Nucleic Acid! Nucleotides!

27 What is the structure of RNA? Single stranded Ribose sugar and phosphate backbone Nucleotides, which are made of what? – Adenine (A) – Uracil (U) – Guanine (G) – Cytosine (C) C pairs with G A pairs with U

28 How are proteins made? RNA copies information from DNA (transcription) RNA leaves the nucleus and takes information to the ribosome Ribosome reads RNA and assembles protein (translation)

29 What types of RNA make proteins? 3 types: – Messenger RNA (mRNA) – carries information from the nucleus to the protein – Transfer RNA (tRNA) – carries amino acids to the ribsome – Ribosomal RNA (rRNA) – makes part of the ribosme

30 What exactly is transcription? Instructions to make proteins are encoded on DNA in nucleotide bases Bases are arranged in triplets (groups of 3) 64 possible triplets (4x4x4) transcription – uses a DNA template to make a complementary RNA strand

31 How is transcription different than DNA replication? RNA Polymerase – enzyme that copies RNA from DNA, DNA Polymerase replicates DNA Only produces 1 strand of nucleotides Uracil is used in place of thymine transcription

32 How does transcription happen? Cell releases chemical signals to start transcription Portion of DNA to be used for transcription is separated RNA polymerase binds at promoter region of DNA Complementary nucleotides are added to RNA strand mRNA is produced DNA reconnects

33 Where does mRNA go? From the nucleus to the cytoplasm to a ribosome (translation) – Where you find ribosomes in a eukaryotic cell? Instructions on mRNA arranged in codons – groups of 3 consecutive bases a codon codes for a certain amino acid or the end of a protein

34 How are codon charts used? Find the first letter in the row “first base” Find the second letter in the row “second base” Find the third letter in the row “third base” Find where the lines intersect = amino acid Practice: AUG GUC ACC GAC UCG UUA AUC AAU CUA AAA GUA GGU AGA CAU GUG GAG GGG UAA

35 Assignment! Complete the transcription translation worksheet Complete the DNA coloring worksheet

36 What exactly is translation? Translation – conversion of the information on mRNA into a sequence of amino acids to make a protein begins after mRNA moves out of the nucleus into the cytoplasm mRNA joins with a ribosome information translated into codons and to amino acids

37 How does the amino acid chain form? Transfer RNA (tRNA) – carries amino acids to mRNA in the ribosome mRNA codons join with anticodons, complementary bases to codons found on tRNA Sequence of the anticodon determines the amino acid it carries - based on shape

38 What does the ribosome do? Ribosomes assembles amino acid into protein Ribosomal RNA (rRNA) – makes up part of the ribosome structure and assists in translation

39 How does tRNA work in the ribosome? up to 2 tRNA molecules can attach to mRNA at once tRNA enters through the A site (aminoacyl) bringing amino acid tRNA moves to P site (peptidyl) where the peptide bond is formed between amino acids tRNA moves to E site (exit)

40 What happens to tRNA when it leaves the ribosomes? tRNA releases from E site after amino acid is attached so another anticodon can be attached to mRNA free tRNA bonds with free floating amino acid in the cytoplasm and can be reused Ribosome continues to attach tRNA until a stop codon is reached

41 Assignment! With your group complete the paper pencil transcription  protein synthesis lab You will need – question guide – template – long paper – glue – At least 1 page of each base – tRNAs – Codon chart – scissors – GTP cap – Honors’ – design your own ribosome with A, P, and E sites

42 What is gene expression? What is a gene? main function of a gene is to control production of protein gene expression – process by which information carried in genes is used to make protein or direct cell activities

43 How does gene expression affect differentiation? multicellular organisms have many cells with the same DNA Cells are not identical due to differences in how genes are expressed only a fraction of genes are expressed at a given time Gene regulation – complex mechanism - determines if a gene is expressed or not

44 Do cells produce different amounts of protein? Yes, the proteins produced depend in part on the environment – cells responding to an injury by producing proteins for repair – antibodies produced when a pathogen is detected length of poly A tail at the end of mRNA determines how long it can survive in cytoplasm

45 What happens when errors occur? Producing too much or too little protein, producing at the wrong time can lead to problems overproduction of some proteins lead to cancer – Cancer occurs when the cell cycle is disrupted causing old or damaged cells to reproduce faster than healthy cells

46 Resources

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