Cell Interactions and Inheritance

Unit Overview

• Duration is 9 weeks

Key Concepts

• The key concept is change
• Related concepts are patterns and interaction
• The global context is personal and cultural expression through products
• Statement of inquiry: Interactions between patterns change products and affect personal and cultural expression

Inquiry Questions

• Factual: What is change?, What are the stages of the cell cycle?, What is mitosis?, What is meiosis?, What is a karyotype?, What are the different modes of inheritance?
• Conceptual: How does the identification of new patterns change our understanding of cell interactions?, How does change in the environment affect inheritance of certain traits?
• Debatable: To what extent does personal and cultural expression change the types of products made to better human life?, To what extent do you think that cloning can be used on humans?, To what extent do you think that Mendel's probabilities are not a "miracle of chance"?

Action

• Direct service: Students will research genetic disorders, create videos and brochures, and give powerpoint presentations to teach grade 8 and 9 students about such disorders.
• Action outcome: Consideration of the ethical implications of their actions.

ATL Skills

• Critical thinking skills are used to solve questions, specifically to identify trends and forecast possibilities.
• Skills needed to write lab reports include using appropriate strategies for organizing complex information and organizing and depicting information logically.

Assessment Criteria

• Criterion A (Knowing and Understanding): Explain scientific knowledge about the cell cycle and genetics; apply scientific knowledge to solve problems; analyze and evaluate information to make scientifically supported judgements about the cell cycle and genetics.
• Criterion B (Inquiring and designing): Explain a problem or question to be tested by a scientific investigation; formulate and explain a testable hypothesis, explain how to manipulate variables, and how sufficient data will be collected; and design a safe, logical, and complete method.
• Criterion C (Processing and evaluating): Collect, organize, transform, and present data correctly in numerical and/or visual forms; interpret data and explain results accurately using correct scientific reasoning; and evaluate the validity of a hypothesis and method, including improvements or extensions.

Content Topics by Week

• Week 1: Revising S1 final exams (8-12/1)
• Week 2: The cell cycle, Sexual and asexual reproduction, The mechanism of mitosis (15-19/1)
• Week 3: Karyotypes and Meiosis (22-26/1)
• Week 4: Mendel: the father of genetics; Patterns of inheritance; Inheritance problems: Monohybrid autosomal traits (29/1-2/2)
• Week 5: Inheritance problems: Codominance and sex linkage (5-9/2)
• Week 6: Inheritance problems: Pedigree charts (12-16/2)
• Week 7-9: Lab report (19/2-9/3)

Command Terms

• Analyse: Break down to identify essential elements, relationships, and interpret information to reach conclusions.
• Annotate: Add brief notes to a diagram or graph.
• Apply: Use knowledge and understanding to respond to a situation or problem.
• Calculate: Obtain a numerical answer.
• Classify: Arrange or order by category.
• Comment: Give a judgement based on a statement or calculation result.
• Construct: Display information in a diagrammatic or logical form.
• Define: Give the precise meaning of a word, phrase, concept, or physical quantity.
• Demonstrate: Make clear by reasoning or evidence.
• Describe: Give a detailed account or picture of a situation, event, pattern or process.
• Design: Produce a plan, simulation or model.
• Determine: Obtain the only possible answer.
• Discuss: Offer a balanced review with arguments, factors or hypotheses, supported by evidence.
• Document: Credit sources by referencing, following a recognized system.
• Draw: Represent by a labelled, accurate diagram or graph, using a pencil.
• Estimate: Obtain an approximate value for an unknown quantity.
• Evaluate: Make an appraisal by weighing up strengths and limitations.
• Explain: Give a detailed account including reasons and causes.
• Find: Obtain an answer showing relevant stages in the working.
• Formulate: Express precisely and systematically the relevant concept(s) or argument(s).
• Identify: Provide an answer from a number of possibilities and state briefly a distinguishing feature.
• Interpret: Use knowledge to recognize trends and draw conclusions from given information.
• Justify: Give valid reasons or evidence to support an answer or conclusion.
• Label: Add title, labels or brief explanation(s) to a diagram or graph.
• List: Give a sequence of brief answers with no explanation.
• Measure: Obtain a value for a quantity.
• Organise: Put ideas and information into a proper or systematic order.
• Outline: Give a brief account or summary.
• Plot: Mark the position of points on a diagram.
• Present: Offer for display, observation, examination or consideration.
• Recall: Remember or recognize from prior learning experiences.
• Select: Choose from a list or group.
• Show: Give the steps in a calculation or derivation.
• Sketch: Represent by a diagram or graph (labelled as appropriate).
• Solve: Obtain the answer(s) using appropriate methods.
• State: Give a specific name, value or other brief answer without explanation or calculation.
• Suggest: Propose a solution, hypothesis or other possible answer.
• Summarize: Abstract a general theme or major point(s).
• Verify: Provide evidence that validates the result.
• Write down: Obtain the answer(s) by extracting information.

Asexual vs Sexual Reproduction

• Asexual reproduction: One parent only. Cells are identical to one another, copies of their parent cell. Required for making body cells, depends on the process of mitosis.
• Sexual reproduction: Two parents involved, a male and a female. Cells are not identical, different compared to their parent cells. Required for producing sex cells (gametes), depends on the process of meiosis.

Advantages and Disadvantages of Sexual Reproduction

• Advantages: May provide new combinations of resistance/variation; Deleterious genes may be deleted; May improve the health of organelles
• Disadvantages: Variation may not offer adaptations to the environment; Finding suitable mates can be slow; Fertilization is not guaranteed.

Cell Cycle Stages

• Interphase: Longest phase, cell growth and metabolic activity. Includes G1 phase (normal cell function and growth), S phase (DNA replication), and G2 phase (preparation for cell division)
• M-Phase: Mitosis where the nucleus divides to produce two identical nuclei including Prophase, Metaphase, Anaphase, and Telophase.
• C-Phase Cytokinesis: Cytoplasm divides, and the cell splits into two identical cells.

Mitosis Phases

• Early Prophase: Spindle microtubules are growing; chromosomes are becoming shorter and fatter by supercoiling
• Late Prophase: Each chromosome has two identical chromatids, held together by a centromere after DNA replication in interphase; spindle microtubules extend from each pole to the equator; the nuclear membrane breaks down.
• Metaphase: Spindle microtubules from both poles attach to each centromere, on opposite sides.
• Anaphase: Centromeres have divided and the chromatids become chromosomes; all chromosomes reach the poles.
• Early Telophase: Spindle microtubules break down, the nuclear membrane forms around the poles.
• Late Telophase: Chromosomes uncoil and are no longer individually visible; the cell divides (cytokinesis) to form two cells with genetically identical nuclei.

Homologous Chromosomes

• Paired chromosomes that are similar in size and carry genes for the same trait.

Chromosome Numbers

• Humans: 46 chromosomes
• Chimpanzees: 48 chromosomes

Diploid vs. Haploid

• Haploid cells have one copy of each chromosome set, represented by n (e.g. human sperm and egg cells have 23 chromosomes).
• Diploid cells have a complete set of chromosomes represented by 2n, e.g. human body cells have 46 chromosomes.

Karyotypes

• The typical number of chromosomes in an organism's body cells.

Recognition Features on Karyograms

• Size of chromosome
• Position of centromere
• Banding pattern

Chromosome 21: Trisomy 21 = Down Syndrome

• 3 chromosomes instead of 2
• Common signs: Short neck, flattened facial profile and nose, small head ears and mouth, upward slanting eyes, wide short hands with small fingers, short attention span, poor judgement, impulsive behavior, slow learning, delayed language and speech development

Chromosome 23: Klinefelter Syndrome (Males)

• 3 chromosomes instead of 2

Signs in teenage boys:

• Taller than average stature; longer legs, shorter torso, and broader hips; absent delayed or incomplete pubertySigns in men: Low sperm count or no sperm; Taller than average height; weak bones; decreased facial and body hair; less muscular compared with other men; enlarged breast tissue and increased belly fat.

Turner's Syndrome (Female)

• Only on chromosome 23, one chromosome instead of 2 (X)
• Non-functioning ovaries cause infertility. Puffiness or swelling of the hands and feet; Skeletal abnormalities; Heart defects; Kidney problems.

Cri du Chat Syndrome

• Chromosome 5 has one of the pairs shorter
• Cry cat syndrome
• A high-pitched cat-like cry; Mental retardation; Delayed development; Distinctive facial features; Small head size; Widely-spaced eyes; Low birth weight and weak muscle tone in infancy.

Asexual Reproduction

One parent only

Cells are identical to one another, they are copies of their parent cell

Required for making body cells

Depends on the process of mitosis

Sexual Reproduction

Two parents involved, a male and a female Cells are not identical, hey are different compared to their parent cells.

Required for producing sex cells (gametes) Depends on the process of meiosis

Gregor Mendel

• The father of genetics.
• Worked on garden peas Pisum sativum. Mendel obtained pure-breeding traits, meaning the offspring are the same for that trait in every generation.
• Plants are self-fertilizing. Mendel removed anthers and fertilized flowers with pollen from another variety resulting in a first filial generation: F1. F1 were left to self-pollinate, producing a variety of features in the second filial generation (F2).
• Findings: Identification of dominant and recessive traits; Mendelian ratio explained how inheritance of traits were obtained, hereditary information is stored in pairs in the adult plant, identification of homozygous and heterozygous traits.

Terms and Definitions

• Homozygous: Genotypes made of the same alleles
• Heterozygous: Genotypes made of two different alleles
• Alleles: Different forms of genes for a single trait
• Dominant: Gene that is always expressed
• Recessive: Gene that is always expressed in the homozygous state
• Trait A distinguishing quality or characteristic

Monohybrid Inheritance

• The inheritance of characteristics controlled by a single gene

Autosomal

Not relating to the sex chromosomes

Punnet Squares

• Used to predict the likelihood of offspring inheriting either short hair or long hair. If the short-haired cat was heterozygote, then the offspring will be either with short hair or long hair, or if it was homozygous, then none of the offspring will be with long hair, all will have short hair.

Cystic Fibrosis

• An inherited disorder in humans caused by a recessive allele in which an important protein is not produced. This protein is responsible for preventing the accumulation of thick and sticky mucus in the breathing tubes. Heterozygote individuals, called carriers, have one allele for the disease and can pass it to their offspring.

Co Dominance

• State all the possible genotypes for the different blood groups shown in the table below. Which blood type is most common, which is least common? [Ai: 1-2] Phenotype / blood type genotype(s) A JAIA, IAI B IBIB, IBi AB AB Ο ii

Sex Linkage

• Unexplained and excessive bleeding from cuts or injuries, or after surgery or dental work • Many large or deep bruises • Unusual bleeding after vaccinations • Pain, swelling or tightness in your joints • Blood in your urine or stool • Nosebleeds without a known cause • In infants, unexplained irritability

Color Blindness

Being 'red/green color blind' doesn't mean people with it mix up red and green only, it means they can mix colors which have some red or green as part of the whole color. So someone with red/green color blindness will probably confuse blue and purple because they can't 'see' the red element of the color purple.

Pedigree Charts

Analyze the pedigree charts below to answer the questions that follow each chart. [Aiii: 5-6]: Use the pedigree below to answer questions 1-5. 3 1 2 I II III IV a. How many males are there? 8 b. How many males have hemophilia? 3 2. A circle represents a female. If it is darkened, she has hemophilia; if open she is normal. a. How many females are there? 8 b. How many females have hemophilia? 2 3. A marriage is indicated by a horizontal line connecting a circle to a square. a. How many marriages are there? 3 4. A line perpendicular to a marriage line indicates the offspring. If the line ends with either a circle or a square, the couple had only one child. However, if the line is connected to another horizontal line, then several children were produced, each indicated by a short vertical line connected to the horizontal line. The first child born appears to the left and the last born to the right. a. How many children did the first couple (couple in row I) have? 2 b. How many children did the third couple (couple in row III) have? 7 5. Level I represent the first generation, level II represents the second generation. a. How many generations are there? 4 b. How many members are there in the fourth generation? 7 Use the pedigree below to answer 6-12 Shaded individuals have Huntington's Disease Hh | hh 6. Write the generation on the pedigree numbers (roman numerals). 7. Which members of the family above are afflicted with Huntington's Disease? I-1, II-2, II-3, II-7, III-3 8. There are no carriers for Huntington's Disease- you either have it or you don't. With this in mind, is Huntington's disease caused by a dominant or recessive trait? Dominant 9. How many children did individuals I-1 and 1-2 have? 6 10. How many girls did II-1 and II-2 have? 2 How many have Huntington's Disease? 1 11. How is individual III-2 and II-4 related? II- 4 is her uncle, 1-2 and III-5? I-2 is his grandmother 12. Write the genotypes of each individual on the pedigree. C- Use the Pedigree below to answer 13-18

• Use of materials and apparatus in the method
• Chemicals must be stated in the specific amounts, that are consistent with the method.
• Correct SI units are needed
• Safety precautions: A short paragraph needs to clarify what measures should be taken throughout the course to prevent harm or injury.
• Method to be done: All steps must be numbered