Lecture 6 BIOSCI

Study Resources

• Access study advice on Canvas page.

• Utilize library resources available through Canvas.

Forgetting Curve

• Human ability to remember decreases quickly over time.

• Importance of space repetition:

  • Review information in varied ways and perspectives to retain.

• Effective strategies for reinforcing memory:

  • Pre-lecture reading to set context.

  • Active concentration during lectures.

  • Organizing and tidying up notes post-lecture.

  • Practice tests and online feedback.

Module Overview

• Focus: Cell structure and function.

• Lecture aims:

  • Ensure comprehension of cellular basics.

  • Material aligns with different program requirements.

• High school biology overlaps, particularly for NCEA Level 2.

Learning Objectives

• Objectives guide the structure and pacing of the lecture.

• All lecture content, including guides, is examinable.

• Variety of question formats will be included in exams.

Cell Theory

• Key concepts:

  • Cell is the basic unit of life.

  • All cells arise from preexisting cells.

  • Universal cellular similarities exist across life kingdoms.

Central Dogma

• DNA transforms to RNA which then translates into protein.

Cell Classification

• Distinction between prokaryotic (bacteria) and eukaryotic (higher organisms) cells:

  • Eukaryotic cells are larger and have membrane-bound organelles.

Cytoplasm Components

• Cytoplasm vs. Cytosol:

  • Cytoplasm: All contents within a cell membrane excluding the nucleus.

  • Cytosol: The liquid part of the cytoplasm.

• Organelles:

  • Nucleus, Endoplasmic Reticulum (ER), Golgi apparatus, lysosomes, etc.

Membrane-Bound Organelles

• Identify which organelles have membranes:

  • Nucleus, ER, Golgi, lysosomes, mitochondria are membrane-bound.

  • Ribosomes are not membrane-bound.

• Endomembrane system: Continuous membranes from ER to Golgi and plasma membrane. Mitochondria and ribosomes not part of endomembrane

Drawing & Labeling Cells

• Practice drawing and labeling cell structures for tests.

• Recognize major components and their functions:

  • Nucleus, ER (rough and smooth), Golgi apparatus, mitochondria, etc.

Plasma Membrane

• Characteristics:

  • Selectively permeable barrier.

  • Composed of a phospholipid bilayer with embedded proteins.

• Hydrophilic heads (likes water) and hydrophobic tails (dislikes water).

Membrane Proteins

• Types:

  • Integral proteins: Span the membrane, often transmembrane.

  • Peripheral proteins: Associate with but do not embed in the lipid bilayer.

• Functions:

  • Transport, enzymatic activity, signal transduction, cell recognition, linking intracellular and extracellular structures.

Nucleus

• Largest organelle with a double lipid bilayer.

• Protects DNA to prevent damage and enables regulated RNA synthesis.

  • Nucleolus: Site of ribosomal RNA synthesis.

Chromatin and DNA Overview

• DNA condenses to form chromosomes during cell division.

• Nucleosomes: DNA wrapped around histones.

• Genes: Approximately 20,000 in human genome, each influencing phenotypic traits.

Ribosomes

• Function in protein synthesis.

• Locations: Free in cytoplasm or bound to rough ER; dictate protein function based on destination.

Endoplasmic Reticulum (ER)

• Rough ER: Ribosome-covered, synthesizes proteins.

• Smooth ER: Lacks ribosomes, synthesizes lipids and detoxifies drugs.

Golgi Apparatus

• Modifies, packages, and distributes proteins and lipids to various destinations.

• Cisternae: Series of folded membranes where modifications occur.

Lysosomes

• Contain digestive enzymes for waste processing and recycling.

• Functions in autophagy (self-eating) and pathogen destruction.

Mitochondria

• Responsible for ATP production.

• Contains its own DNA and ribosomes, critical for energy metabolism.

Cytoskeleton

• Provides structure and shape:

  • Microfilaments: Smallest, composed of actin, allows movement.

  • Intermediate filaments: Stabilize cell structure, made of keratin.

  • Microtubules: Largest, support organelle movement and are essential in cell division.

General Features of Cells

• Cells share common structural traits while being specialized for various functions.