How does a cell control all of its

How does a cell control all of its activities? PROTEINS!! üStructural – for building cell parts üEnzymatic – for performing chemical activities

What controls (codes for) the proteins in your cells? DNA SO… ultimately, cells are controlled by DNA.

Quick Quiz!! What is the blueprint for a cell? 1. Proteins 2. DNA 3. RNA

Quick Quiz!! What has direct control of a cell’s function? 1. Proteins 2. DNA 3. RNA

Quick Quiz!! What ultimately determines how proteins are put together? 1. Proteins 2. DNA 3. RNA

DNA – The Discovery • James Watson and Francis Crick (1950’s) – Developed DNA model – Based model on clues from other scientists • Rosalind Franklin’s X ray diffraction • Cell changes in response to viral injections (Hershey-Chase Experiment) • Mitosis & meiosis demonstrate dramatic changes • Species specific contents • Base pairs in equal amounts (Chargaff’s Rules) These observations led scientific community to agree that DNA was the carrier of genetic material and inspired Watson and Crick to develop their model. Won the Nobel Prize in 1962

DNA Model Helical Structure Coiling due to hydrogen bonds Double Stranded Nucleotides link together to create each strand. Each Nucleotide consists of A phosphate group A sugar group (Deoxyribose) And a nitrogenous base

Complimentary Base Pairs Base Pairing: Links two sides into double stranded molecules Complimentary Bases bond with hydrogen bonds Pyrimidines link to Purines Thymine (T) to Adenine (A) Cytosine (C) to Guanine (G) T A Purines 2 bonds C G 3 bonds Pyrimidines

Quick Quiz!! Which nitrogenous base is pictured below? 1. 2. 3. 4. Adenine Thymine Guanine Cytosine Deoxyribose ? Phosphate Group

DNA Replication To produce new daughter cells (cell reproduction) DNA must be copied and passed on. This process is controlled by a set of enzymes called DNA Polymerases Replication Video

DNA Replication Step 1: - Enzyme unzips double helix by breaking apart complimentary bases - Process occurs at several spots along molecule creating replication “bubbles”

DNA Replication Step 2: - Enzyme holds complimentary bases in place using the old strand as a template/pattern. - Nucleotides are plugged into specific sites according to the rules of complimentary base pairing

DNA Replication Step 3: - New nucleotides connect to each other to form the sugar phosphate backbone - “Bubbles” extend in both directions along the molecule and eventually merge, forming a completed strand of DNA - Two DNA strands are being made, each consist of one old part and one newly formed part

DNA REPLICATION PRACTICE

Protein Synthesis Process that makes proteins. Proteins are then used as structural components or as enzymes to control chemical reactions in cells. Proteins Two Parts: Transcription - formation of m-RNA from DNA pattern Translation – reading message to arrange amino acids in order to create polypeptide

Transcription Step 1: RNA polymerase finds promoter on DNA and starts unzipping the double helix

Transcription Step 2: Another enzyme begins plugging in RNA complimentary bases DNA nitrogenous bases: adenine thymine guanine cytosine RNA nitrogenous bases: adenine uracil guanine cytosine RNA uses uracil instead of thymine

Transcription Step 3: RNA nucleotides link together to join sugar phosphate backbone

Quick Quiz!! If the following piece of DNA is transcribed, what sequence would the RNA read? 1. 2. 3. 4. 5. TTAGCAATGGGC GGCTACCGTTTA AATCGTTACCCG UUAGCAAUGGGC AAUCGUUACCCG AATCGTTACCCG

Transcription Step 4: Completed messenger RNA strand detaches from DNA and travels to the ribosome carrying the pattern DNA rewinds

Transcription RNA is edited before being read: Introns are edited out Extra DNA not needed to code for protein Exons remain DNA used to code for protein Pre-m. RNA Exon Intron Exon m. RNA Editing occurs in the nucleus Intron

Translation Occurs in the ribosome (made of r-RNA) Step 1: Bring part of m-RNA strand into ribosome Step 2: Bring complimentary t-RNA (anticodon) to match m-RNA (codon) T-RNA is carrying specific amino acid Amino Acid

Translation Amino Acid carried by each t-RNA is predetermined according to a code Each codon (group of 3 nitrogenous bases in m-RNA) specifies 1 amino acid Allows the set of 4 nitrogenous bases to code for the set of 20 possible amino acids Rearrangement of 20 amino acids allows for unlimited number of proteins

Translation One codon signals for the start: AUG It codes for what amino acid? Three codons signal translation to end: What are they?

Translation Step 3: Bring in next t-RNA. When the amino acid on the second t. RNA is close enough to the amino acid on the previous t-RNA, a bond will form. PEPTIDE BOND

Translation Step 4: When peptide bond is formed, first t-RNA will release from m-RNA and will leave the ribosome to search for another amino acid.

Translation Step 5: Process repeats until the long polypeptide is built and ribosome reaches a “stop” codon on the m-RNA strand. At that point, the last t-RNA releases the protein and the protein, t-RNA, and m-RNA leave the ribosome. M-RNA is broken down into nucleotides.

AMAZING LINKS TRANSLATION translation video Seeing a protein from blueprint through use.

Quick Quiz!! If the following piece of DNA is used for protein synthesis, what sequence of amino acids would be in the polypeptide? 1. Leucine-alaninemethionine 2. Asparaginearganine-tyrosine 3. Histidine-cysteinetyrosine AATCGTTACACT

Proteins • Once a polypeptide chain is created it is folded into its final shape in the ER or in the Golgi Apparatus • Shape is very important to how proteins function

Enzymes Lock and Key Theory: Enzymes control chemical reactions: (2 types of chemical reactions) 1. ) Using enzymes to digest molecules: Substrates connects to enzyme at active site Creates enzyme substrate complex Enzyme separates substrates to help break bonds Enzyme can be reused to do this over and over again!!

Enzymes Lock and Key Theory: Enzymes control chemical reactions: (2 types of chemical reactions) 2. ) Using enzymes to build molecules: Substrates connects to enzyme at active site Creates enzyme substrate complex Enzyme bring substrates together to help make bonds Enzyme can be reused to do this over and over again!!

Mutations and Proteins • Mutations are changes in the DNA • Mutations can cause different sequences of amino acids • If the wrong polypeptide chain is made, the final protein will be shaped incorrectly • The final protein (enzymatic or structural) can be defective OR can be beneficial

Mutations get passed from one generation to the next when cells copy the mistakes in DNA Copied mistakes go into daughter cells during cell division To produce the next generation in sexually reproducing organisms cells experience: Meiosis

Cell Division occurs in two ways: Mitosis produces genetically identical daughter cells Meiosis produces genetically different offspring

Chromosome Changes Most normal cells start with “n” number of pairs of chromosomes n = number of kinds of chromosomes 2 n = total number of chromosomes Examples: Onion Fly Human n 4 8 23 2 n 8 16 46 How Many Chromosomes Does It Have? Fathers donate sex cell with half a set of chromosomes = 23 Offspring receives full set of chromosomes = 46/23 pairs Mothers donate sex cell with half a set of chromosomes = 23 Diploid cells – 2 n chromosomes Haploid cells – n chromosomes, ½ set

Quick Quiz!! If a certain cell has 10 total chromosomes, what number of types of chromosomes does it have? A. B. C. D. 10 5 20

Quick Quiz!! If the cells of a sexually reproducing organism have 16 chromosomes, how many were likely to be donated from it’s father? A. B. C. D. 32 16 8 4

Quick Quiz!! If you have a diploid cell with 12 kinds of chromosomes, how many total chromosomes are in the cell? A. B. C. D. 24 12 13 6

Quick Quiz!! If you have a haploid cell with 12 kinds of chromosomes, how many total chromosomes are in the cell? A. B. C. D. 24 12 13 6

Meiosis Only used to create sex cells have n number of chromosomes Human = 23 Onion = 4 Sperm Ovum/Egg

Quick Quiz!! How are sex cells genetically different from other body cells? A. They are not different B. They result in new species C. They have half the number of chromosomes

Stages of Meiosis occurs over two separate sets of stages, Meiosis 1 and Meiosis 2. Let’s examine how this works with a cell that has 6 chromosomes

Prophase I Homologous chromosomes form, find each other and become tetrads Spindle forms Nucleus breaks up

Metaphase I Tetrads line up in the middle of the cell Spindle fibers attach to centromeres

Anaphase I Tetrads split Homologous chromosomes move to opposite ends of the cell Cell begins cytokinesis

Telophase I Two haploid daughter cells are created Meiosis 2 may begin immediately

Quick Quiz!! In the previous slide, what does n=? A. B. C. D. E. F. G. H. 1 2 3 4 6 8 10 12

Prophase II Spindle fibers form Nucleus breaks apart

Metaphase II Individual Chromosomes line up in the center of the cell Spindle fibers attach to centromeres

Quick Quiz!! How is Metaphase II different from Metaphase I of meiosis? A. It isn’t, they are exactly the same B. In Metaphase II, the chromosomes don’t line up C. In Metaphase I, tetrads lined up, not individual chromosomes D. In Metaphase I, the spindle fibers did not attach

Anaphase II Sister chromatids separate Chromatids move to opposite ends of the cell Spindles shorten Cytokinesis begins

Telophase II Cytokinesis ends Four haploid cells are left In most males, all four will become gametes In females, only one will

Gametogenesis = formation of gametes Gametes: haploid sex cells, contain n number of chromosomes Occurs slightly differently in males and females Spermatogenesis = sperm Oogenesis = egg

Gametogenesis Spermatogenesis Oogenesis XX xx X x X x I I I I Gametes I I I I Sperm Egg or Ovum II II 3 nonfunctional polar bodies Fertilization: sperm DNA enters egg, completing the set of chromosomes

Quick Quiz!! After fertilization, what is the n number of the cell in the last slide? A. B. C. D. 2 4 8 16