Cells

All living things are made of cells. All of the living things in these pictures have something in common about the way they are made up. What is it?

What is a Cell? A cell is the basic building block of living organisms. They were named by Robert Hooke who used the first microscope to look at cork in 1665. He named the structures he saw cells because they looked like monks’ cells.

An etching of cork bark from Hooke’s 1665 first edition of Micrographia

Eukaryotic Cells Cells can be split into two main categories: Prokaryotic cells Eukaryotic cells Prokaryotic cells don’t have a nucleus Can you think of any examples? Eukaryotic cells have a nucleus Eukaryotic cells also contain sub-cellular structures called organelles. Bacteria Plant and animal cells

Plant and Animal Cells – what can you remember? Which is an animal cell and which is a plant cell? Complete the worksheet to name the structures (organelles) you can remember in the plant and animal cells. Write the function (job) of each cell part.

Animal Cell Plant Cell Vacuole nucleus Cell membrane Cell wall Chloroplasts Cell wall Mitochondria Cell membrane Ribosomes Ribosomes Mitochondria nucleus

Structure Job Nucleus Contains genetic material / DNA – the set of instructions that controls the cell. Cell membrane Controls what enters and leaves the cell. Cell wall Provides strength and support to plant cells. It is found outside the cell membrane. Mitochondria This is where aerobic RESPIRATION happens. This is the process that releases ENERGY from glucose. Ribosomes They produce proteins from amino acids (protein synthesis) Vacuole Stores cell sap. In plants this is a large permanent structure. It also helps support the cell. Chloroplast This is where PHOTOSYNTHESIS happens –the process where plants use sunlight to make glucose. Contains a green pigment called chlorophyll.

Estimating Size What is an estimate? Use the scale bar to estimate the length and width of these cells.

Calibrating a microscope How can we estimate the size of an object we are viewing down the microscope? If we know the size (diameter) of the field of view, we use this to estimate the size of the object. Put a ruler on the stage and focus on it on low power Use the ruler to measure the diameter of the field of view in millimetres Work out the total magnification for low power. Use this to work out the diameter of the field of view on medium and high power.

Animal Cell A picture taken using a microscope is called a micrograph. Plant cell Nucleus Cell wall Cytoplasm

Quick Quiz What is an estimation? an approximate value Name one part you could find in a plant cell but not an animal cell. cell wall, chloroplasts, permanent vacuole What process happens in a mitochondrion? aerobic respiration © Pearson Education Ltd 2015. Copying permitted for purchasing institution only.

Quick Quiz What is one function of a plant cell’s permanent vacuole? to help keep the cell rigid/to store substances In which part of a plant cell is cell sap stored? vacuole In which part of a cell would you find chromosomes? nucleus © Pearson Education Ltd 2015. Copying permitted for purchasing institution only.

Quick Quiz When you look down a microscope, what is the area that you see called? field of view Why can an electron microscope detect smaller structures in cells than a light microscope? it has better magnification and better resolution © Pearson Education Ltd 2015. Copying permitted for purchasing institution only.

Quick Quiz What is a picture taken with a microscope called? micrograph Some microscope pictures have a small line drawn on them with information about how long the line is when unmagnified. What is this line called? scale bar © Pearson Education Ltd 2015. Copying permitted for purchasing institution only.