Biology Chapter: Cell Structure and Function

Starter Activity

• Students were asked a question and were given mini whiteboards to write their answers on.

Mitochondria

• Sometimes called the powerhouse of the cell
• Releases energy in respiration
• Contains DNA and controls cell activities
• Responsible for protein synthesis
• Found in all prokaryotes but only some eukaryotes
• An organelle found in plant cells, algae, and some prokaryotes

Learning Objectives

• Specialised cells and magnification calculations
• Describe how specialised cells are adapted to their function

Cell Types (Diagram)

• Two cells are shown, a Phagocyte and a Lymphocyte, with labels for the nucleus and cytoplasm.

Red Blood Cells

• Structure:
  • Biconcave shape for maximum surface area for oxygen diffusion
  • Contains haemoglobin to carry oxygen
  • No nucleus to increase space for haemoglobin
  • Small and flexible to fit through capillaries
• Function:
  • Carries oxygen from the lungs to the body and carbon dioxide from the body to the lungs

Phagocyte

• Structure:
  • Flexible shape to engulf microorganisms
  • Lobed nucleus
• Function:
  • Found in blood
  • Attracted to diseases and bacteria
  • Engulfs bacteria/pathogens to prevent infection

B Lymphocyte

• Structure:
  • A type of white blood cell with surface receptors
• Function:
  • Produces specific antibodies to destroy pathogens
  • Recognises pathogens via antigens (foreign proteins)
  • Reproduces quickly to create more antibodies to neutralize pathogens

Neuron

• Structure:
  • Extremely elongated (long) cells with branches at both ends to connect to other nerve cells
  • The axon (main branch) has a myelin sheath (fat) to prevent electrical impulses affecting other parts of the body
• Function:
  • Carries nerve impulses throughout the body

Sperm Cell

• Structure:
  • Long tail for swimming to the egg
  • Enzymes in the head (acrosome) to penetrate the egg's outer coating
  • Many mitochondria for energy for locomotion
  • Made in the testes of males
• Function:
  • Carries the father's DNA to the egg for fertilization

Root Hair Cell

• Structure:
  • Large surface area to absorb water
  • Thin cell wall for easy water passage
  • Lacks chloroplasts
  • May contain many mitochondria for active transport of mineral ions
• Function:
  • Absorbs minerals and water from the soil

Palisade Cell

• Structure:
  • Tall shape with large surface area for capturing sunlight
  • Packed with chloroplasts for sunlight absorption
  • Found beneath the epidermis for shorter light travel distance
  • Regular shape for efficient packing
• Function:
  • Carries out photosynthesis

Ciliated Cell

• Structure:
  • Lines air passages and oviducts
  • Has tiny hairs called cilia
• Function:
  • Prevents lung damage by wafting mucus containing dust and bacteria out of the lungs
  • Moves the ovum through the oviduct
  • Cilia die when exposed to smoke causing mucus buildup & smoker's cough

Ovum

• Structure:
  • Contains large amounts of cytoplasm with organelles
• Function:
  • Stores energy for a developing embryo
  • Carries the mother's DNA for fertilization

Rods and Cones

• Structure:
  • Specialized cells with outer segments containing photosensitive chemicals and nuclei.
• Function:
  • Responsible for sight

Guard Cells

• Structure:
  • Cells surrounding stomata (pores) with a thick inner wall and thin outer wall
  • Contain chloroplasts
• Function:
  • Regulate water loss (transpiration)

Magnification Calculation

• Formula: magnification = size of image / actual size of specimen
• A triangle diagram illustrating the relationship between magnification, image size, and actual size is provided.
• This formula is used to determine the actual size if image size and magnification are known or vice versa.

Units of Measurement

• Millimeters (mm), micrometers (µm), and nanometers (nm) are commonly used in microscopy
• Important conversions are shown: 1 m = 1000 mm, 1 mm = 1000 µm, and 1 µm = 1000 nm
• Methods for converting measurements are explained.

Further Examples

• Several examples of converting units like the diameter of an arteriole (1.5 mm to µm or a mitochondrion of 2 µm to nm or a chloroplast of 10,500 nm to µm) have been shown.

Taboo Words

• A list of words the students are prohibited from using during the activity is provided
• Words from different types of specialized cells covered, and various body systems for which these cells are useful for.

This quiz covers important aspects of cell biology, including the structure and function of organelles like mitochondria and specialized cells such as red blood cells. Students will explore the adaptations of various cell types, their roles in the body, and perform magnification calculations related to cell diagrams.