Cell Structures and Microscopy

• Bacterial cells are different from animal cells
• Plant cells have structures not found in bacterial or animal cells
• Specialized cells have specific jobs

Sperm Cell Structure

• The long tail helps with movement
• Aids sperm reach its destination
• Mitochondria provide energy for the sperm to function

Figure 1 - Human Cheek Cell

• Cheek cells are a type of body cell
• Body cells grow through cell division
• A light microscope is used to view human cheek cells
• Mitosis is the name for cell division in body cells
• Ribosomes and mitochondria are not shown on Figure 1
• An electron microscope is needed to see ribosomes and mitochondria
• Electron microscopes use higher magnification

Calculations

• Cheek cell is magnified 250 times
• Calculate width of cheek cell in micrometers (µm)
• Red blood cell is 8 µm in diameter
• Bacterial cell is 40 times smaller than red blood cell
• Calculate diameter of the bacterial cell

Antibiotics and Bacteria

• Antibiotics, A, B, C, D and E and their affect on a type of bacterium, are being tested
• Bacteria are grown on agar jelly in a Petri dish
• Paper discs soaked in each antibiotic are placed on the bacteria in the Petri dish
• The Petri dish isput in an incubator
• The maximum temperature the incubator should be set at is being tested
• Incubators should not be set at a higher temperature
• High temperatures might help the growth of pathogens
• To determine the best antibiotic to treat a disease
• Antibiotics are not effective against viruses

Cell Types

• Given diagrams of four types of cells (A, B, C, and D)
• Tasked to identify plant cells
• Note a reason for the choice
• Identify a cell adapted for swimming
• Specify which cell can produce glucose by photosynthesis
• To recall which process oxygen is used for
• Cells A, B, C and D all use oxygen during respiration

Cell Identification - A and B

• Cell parts A and B are to be identified
• Cell A is the cell membrane
• Cell B is the cytoplasm
• Animal cells and plant cells have differences
• Two differences are needed to identify an animal over a plant cell
• Oxygen diffuses into cells
• Use information from the diagram to justify your answer
• Cells are usually found with other similar cells
• A group of similar cells constitute a tissue

Sour milk transfer experiment

• A student transferred sour milk from a bottle to a Petri dish of nutrient agar
• Step 1: Heat a wire loop in a flame
• Step 2: Place the wire loop on the bench to cool
• Step 3: Remove a drop of sour milk from a bottle using the wire loop
• Step 4: Raise the lid of a Petri dish of sterilized nutrient agar
• Step 5: Spread the sample of sour milk across the nutrient agar
• Step 6: Replace the lid and put the Petri dish in an incubator at 25°C for 2 days"
• There are a list of four actions carried out
• Match the action to a possible effect

Stomach Lining

• Identify structures A and B
• A is the cell membrane
• B is the cytoplasm
• The function of the nucleus is to control the activities of the cell
• Match parts of the human body to correct scientific name
  • Layer of cells lining the stomach - A tissue
  • Stomach - An organ
  • Mouth, stomach. intestines, liver and pancreas - An organ system

Components of the Nucleus

• Genes are part of chromosomes in the nucleus of a cell
• Genes control various an organism's characteristics
• Studying the similarities and differences between organisms helps classify them
• Living things cab be grouped into animals, microorganisms and plants

Growing bacterial cultures

• Growing pure cultures of a bacterium
• Use of apparatus A and apparatus B in experiment
• Both Apparatus A and B need to be sterilized
• Should be sterilized to prevent contamination
• apparatus A is sterilized by using a flame
• Apparatus lid B should be securely taped in place
• Securing reduces contaminations
• The top temperature to grow bacteria, in schools is 25 °C

Yeast Cell Structure

• Human cells and yeast cells have some similar parts
• Label parts in a yeast cell diagram on the diagram
• Some cells readily divide to form new cells
• For example, human skin cells divide to replace skin cells
• Such division repairs the epidermis
• Human stem cells can become many types of human cells
• Stem cells may from embryos
• paralysis, stem cells be used treat