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Period 1 Lesson 14.1 RNA VS DNA.

How does RNA differ from DNA?. [image] RNA Single stranded Contains sugar ribose Adenine pairs with uracil Synthesized when needed Nucleic acid Made of nucleotides uses guanine, cytosine, and adenine DNA Double stranded Contains sugar deoHt•ibose Adenine pairs with thymine Always stored in cell nucleus.

How does RNA differ from DNA?. DNA: Master Plan Has all the instructions. Stays safe in the “office” (nucleus). RNA: Blueprint Copy Cheap, disposable copy of the master plan. Taken to the “building site” (ribosome) to make proteins..

How does RNA differ from DNA?. RNA has many roles, one of which is protein synthesis. RNA controls the assembly of amino acids into proteins. There are three main types of RNA involved in protein synthesis: mRNA (Messenger RNA) Carries instructions from DNA in the nucleus → to ribosomes in the cytoplasm. Tells the cell what protein to build. tRNA (Transfer RNA) Brings amino acids (the “building blocks”) to the ribosome. Matches each amino acid to the coded message on the mRNA. rRNA (Ribosomal RNA) Forms part of the ribosome itself. Helps assemble proteins by joining amino acids together..

Period 2 Lesson 14.2 Protein Synthesis.

Transcription. Definition: Transcription is the process of making RNA from DNA. Location: In prokaryotes: transcription and translation both happen in the cytoplasm. In eukaryotes: transcription happens in the nucleus; translation in the cytoplasm. Key Enzyme: RNA polymerase binds to DNA, separates the strands, and uses one strand (the template strand) to build RNA. RNA polymerase only binds to promoters, special DNA sequences that signal where to start transcription. Other DNA regions act as stop signals, telling the enzyme when the RNA strand is complete..

Transcription. Process DNA strand unwinds. RNA polymerase matches complementary RNA nucleotides to the DNA template (A → U, T → A, C → G, G → C). A strand of mRNA is formed. Result: The mRNA carries the genetic code from the DNA in the nucleus to the ribosome in the cytoplasm, where it will be used to build proteins..

Transcription.

Correct answer: C. Quick Check. A molecular biologist is developing a computer model of the transcription of a gene into RNA. Which event should be included in the model before transcription occurs?.

How does RNA differ from DNA?. With your partner, study the diagram and discuss: What parts are removed from the RNA strand? What parts are kept and reconnected? Why might a cell go through all this editing? Write your answers in 1–2 sentences in your copybook or on a sticky note..

ANSWERS: Q1. What parts are removed from the RNA strand? Introns are removed because they do not code for proteins. Q2. What parts are kept and reconnected? Exons are kept and spliced together to form the final mRNA strand. Q3. Why might a cell go through all this editing? To create a correct and useful mRNA sequence that codes for the right protein, and sometimes to allow one gene to make different proteins..

RNA Editing Newly made RNA is like a first draft, it needs editing before it can be used. These early molecules are called pre-mRNA. Introns are parts of the RNA that are cut out and discarded. Introns = “interrupting” sequences that don’t code for proteins. Exons are the parts that remain and are spliced together to form the final mRNA. Exons = “expressed” sequences that code for proteins. This editing happens in the nucleus, before the RNA moves to the cytoplasm. Scientists believe RNA editing allows: 1- One gene to make different mRNA molecules in different tissues. 2- Small changes in DNA to cause big effects in how genes function, important for evolution..

Option 2: RNA Editing in Smart Crops A researcher identifies the nucleotide sequence AAC in a long strand of RNA inside a nucleus. In the genetic code, AAC codes for the amino acid asparagine. When that RNA becomes involved in protein synthesis, will asparagine necessarily appear in the protein? Use specific content to support your argument. ANSWER: Not necessarily. The RNA sequence might still undergo RNA processing before translation. During RNA splicing, introns (non-coding sections) are removed and only exons (coding sections) remain. If the AAC codon is located within an intron, it will be removed and not appear in the final mRNA. Therefore, asparagine will only appear in the protein if AAC remains in the mature mRNA after splicing..

Lesson Title: 14.2- Ribosomes and Protein Synthesis.

Summary Notes: The Genetic Code What are the 4 bases of RNA? The four RNA bases (A, U, C, G) make up the genetic code. Why do codons need 3 bases instead of 1 or 2? Codons = groups of 3 RNA bases. How many amino acids does 1 codon specify? Each codon codes for 1 amino acid. Some amino acids are coded by more than one codon. Which codon always starts translation, and what amino acid does it bring? AUG = start codon (Methionine). Why do we need stop codons, and what happens when the ribosome reaches one? UAA, UAG, UGA = stop codons (end translation)..

Why AUG? How does this match? What is the ribosome’s role?.

What’s happening here? Why does everything stop here?.

Correct answer: D. Velma is developing a computer model of translation. Her instructor points out that the model does not include ribosomes or ribosomal RNA. If the model is accurate in other ways, how does the absence of ribosomes and ribosomal RNA affect it? a. Certain amino acids would be missing from the polypeptides. b. The polypeptides would be much longer than normal. c. Amino acids would be joined together in an incorrect order. d. Amino acids would not join together, and no polypeptides would form..

c NUCLEUS CYTOPLASM Visual Summary Figure 14-7 Overview of Transcription and Translation DNA encodes the information for an organ- ism's traits. mRNA transcribes the genes, and then tRNA builds the proteins. These proteins produce the organism's traits. T Transcription codon DNA strand mRNA C' coob0 Polypeptide Ribosome Lysine tRNA mRNA Translation.

1- Suppose you start with the DNA strand ACCGTCACT. What three amino acids does the complementary mRNA strand code for?.

ANSWERS: Question 1: DNA strand: ACCGTCACT Step 1 – Find the complementary mRNA strand DNA → mRNA base pairing: A → U T → A C → G G → C So, DNA: A C C G T C A C T mRNA: U G G C A G U G A Step 2 – Group into codons (triplets): UGG – CAG – UGA Step 3 – Use the codon chart: UGG → Tryptophan (Trp) CAG → Glutamine (Gln) UGA → Stop codon Answer: The mRNA strand codes for Tryptophan – Glutamine – Stop..

Question 2 Construct a two-column table for the given amino acids:.

Figure 14-5 The Genetic Code To interpret this diagram, read each codon from the inner circle to the outer circle. For example, the codon CAC codes for the amino acid called histidine. Use Models Which uo codons code for glutamic acid? 6 c 44 Valine Arginine c c c c G A U c serine U c c c G Acu c c U cysteine c Stop G ryptophan A Leucine c c c GA 4. GA c U O •O. 3 60 O To decode the codon CAC, find the first letter in the set of bases at the center of the circle. @Find the second letter of the codon A, in the "C" quarter of the next ring. Find the third letter, C, in the next ring, in the "C-A" grouping. O Read the name of the amino acid in that sector—in this case histidine..

Option 1: From Codon to Disease – Sickle Cell Example Use the codon chart to fill in the amino acids coded by the sequences in the diagram: Normal DNA: __________ Sickle Cell DNA: __________ Compare the amino acid sequences. Answer these questions: How does this single amino acid change affect the protein? Why does it change the shape of the red blood cell? How might this lead to health problems?.

Option 1: From Codon to Disease – Sickle Cell Example Normal DNA: G A C T T C T T → mRNA: C U G A A G A A → Amino acids: Leu – Glu – Glu Sickle Cell DNA: G G A C A T T T → mRNA: C C U G U A A A → Amino acids: Pro – Val – Lys Compare the amino acid sequences: Normal: Leu–Glu–Glu Sickle Cell: Pro–Val–Lys The second codon changes Glu → Val — this is a missense mutation..

Answer the questions: 1. How does this single amino acid change affect the protein? It alters the structure of the hemoglobin protein, making it less soluble and prone to sticking together. 2. Why does it change the shape of the red blood cell? The abnormal hemoglobin molecules clump and distort the red blood cell into a sickle (crescent) shape, instead of a round one. 3. How might this lead to health problems? Sickle-shaped cells can block blood vessels, reducing oxygen delivery. This causes pain, fatigue, organ damage, and anemia..

Lesson Title: 14. 4- Mutations. Monday, October 13, 2025.

What Are Mutations? A mutation is a change in DNA, like a small “spelling mistake” in the genetic code. Mutations can happen when cells copy DNA and accidentally insert, skip, or replace a base. They are heritable, meaning they can be passed to new cells or offspring. Mutations may affect: Gene (Point Mutation): typically involves 1 to several nucleotides. Chromosomes: involves large segments of DNA, from hundreds to millions of nucleotides..

[image] MUTATIONS OR CHANGES IN GENES OR CHROMOSOMES GENE MUTATIONS CHROMOSOME MUTATIONS Replacement of one Nucleotide by another Addition or Deletion of a Nucleotide Change in the number of Chromosomes (e g. polyploidy, aneuploidy) Change in the Structure of a Chromosome.

Cell Nucleus Chromosome Centromere Telomere DNA Gene.

Types of Mutations: Gene mutations (Point Mutations).

Types of Mutations: Gene mutations (Point Mutations).

Substitution Mutations Types. Type of Substitution Mutation Description Example Effect on Protein Silent Mutation Mutated codon codes for the same amino acid CAA → CAG (both code for glutamine) No effect — protein stays the same Missense Mutation Mutated codon codes for a different amino acid CAA → CCA (glutamine → proline) Variable — may slightly or seriously change protein function Nonsense Mutation Mutated codon becomes a premature stop codon CAA → UAA (glutamine → STOP) Usually serious — protein chain stops early and becomes incomplete.

Insertions and Deletions (Frameshift Mutations) A base is added (insertion) or removed (deletion) from the DNA sequence. This causes the reading frame (groups of 3 bases = codons) to shift. The shift changes every codon after the mutation. As a result, the protein made is completely different and often nonfunctional. These are called frameshift mutations because they “shift” how the code is read. ➡️ 1 base added or removed = big change! ➡️ Frameshift = changes all amino acids after the mutation..

The diagram shows the effect of a point mutation on a section of a gene. The nitrogenous base adenine (“A”) is inserted into the sequence. (Note: The diagram shows the base sequence of DNA in the top row, and the transcribed mRNA in the bottom row.) What best describes this mutation and its effect on the protein that the gene produces? a. It is a missense mutation that changes exactly one amino acid. b. It is a nonsense mutation that has no effect on the protein. c. It is a frameshift mutation that changes many amino acids. d. It is a frameshift mutation that changes exactly one amino acid..

[image] MUTATIONS OR CHANGES IN GENES OR CHROMOSOMES GENE MUTATIONS CHROMOSOME MUTATIONS Replacement of one Nucleotide by another Addition or Deletion of a Nucleotide Change in the number of Chromosomes (eg. polyploidy, aneuploidy) Change in the Structure of a Chromosome.

Types of Mutations: Chromosomal mutations. [image] NUMERICAL CHROMOSOMAL INSTABILITY STRUCTURAL CHROMOSOMAL INSTABILITY A Small-scale gains Trisomy Small-scale losses Monosomy c A B Inversions Deletions Amplifications Large-scale gains Normal set of chromosomes c D Translocations Flip Extra set (polyploidy).

Chromosomal Mutations Chromosomal mutations involve changes in the number or structure of chromosomes. These mutations can change the location of genes on chromosomes and can even change the number of copies of some genes. There are four types of chromosomal mutations: deletion, duplication, inversion, and translocation..

Types of Mutations: Chromosomal Mutations. Deletion involves the loss of all or part of a chromosome..

Inversion reverses the direction of parts of a chromosome..

Mutagens. Some mutations arise from mutagens, chemical or physical agents in the environment. Chemical mutagens include certain pesticides, a few natural plant, tobacco smoke, and environmental pollutants. Physical mutagens include some forms of electromagnetic radiation, such as X-rays and ultraviolet light. If these mutagens interact with DNA, they can produce mutations at high rates. Cells can sometimes repair the damage; but when they cannot, the DNA base sequence changes permanently..

Mutations: Helpful or Harmful?. Mutations are changes in DNA that can affect genes or chromosomes. Their effects vary: some have no impact, some are beneficial, and others are harmful. They create genetic diversity, which is important for evolution. Harmful Mutations Change protein structure or gene activity in a negative way, producing defective proteins that disrupt normal body functions. May lead to genetic disorders or diseases such as some cancers. Example: Xeroderma pigmentosum : a mutation that stops DNA repair after UV exposure, causing extreme sensitivity to sunlight. Can cause uncontrolled cell growth (e.g., cancer) due to damaged DNA..

Mutations: Helpful or Harmful?. Helpful Mutations Produce proteins with new or improved functions that help organisms adapt. Example: Mosquitoes developed resistance to pesticides, harmful for humans, beneficial for mosquitoes. Some human mutations increase bone density or resistance to HIV. Polyploidy (extra sets of chromosomes) in plants makes fruits larger and stronger, seen in bananas, limes, and strawberries. Breeders use helpful mutations to create better crop varieties..

Answer in your notebook / ClassPoint (2–3 min):. [image] Q.2. • Use the words in the box below to label the types of mutations. Deletion Duplication Translocation Insertion 1 Inversion.