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Biology B2Lesson 2: Bacteria
Connect: Exam Practice (a) The diagrams show a bacterial cell, a plant cell
and an animal cell. Structure X is found in all three cells.
(i) Complete the sentence by choosing the correct answer. Structure X is the (1):
A cell membrane B cell wall C cytoplasm D nucleus
Connect: Exam Practice (ii) Many bacteria have one or more flagella whereas most
animal cells have no flagella. State one other difference between a bacterial cell and an animal cell. (1)
(b) (i) Scientists use microscopes to magnify cells. Choose from the following words to complete the sentences. (2)
Focusing wheel less objective lens Light more
The magnification of a light microscope can be varied by changing the ______________. The electron microscope can magnify images _____ than the light microscope.
Connect: Exam Practice (ii) The diagram shows a sperm cell that has been magnified
100000 times.
Calculate the actual length of the sperm cell. (2) Length of sperm cell = ....................................................................
mm
(iii) Explain why a human sperm cell contains more mitochondria than most other types of cell in the human body. (2)
Connect: Exam Practice (a) (i) A (1)
(a) (ii) Any one of the following points bacterial cells have a cell wall (animal cells do
not) (1) bacterial cells do not have a nucleus (animal
cells do) (1) bacterial cells have circular DNA /
chromosomal DNA (animal cells do not) (1) bacterial cells have plasmids (1)
Connect: Exam Practice (b) (i) objective lens (1) more (1) (2) (b) (ii) calculation (1) correct answer (1) = 0.00130 / 1.3 × 10-3 (2) (b)(iii) An explanation including two of the
following points: mitochondria are sites of respiration for
energy (1) sperm requires a lot of energy (1) for movement / swimming / to move the
flagellum (1) (2)
What Are We Learning By the end of this lesson, you should:
Be able to describe the structure of a bacterial cell.
Relate the structure to the function of a bacterial cell.
SMSC & RWCM During this lesson, you will be
developing social skills by working in groups.
We will be developing listening skills and will be using key words in the correct context.
Progress Step 1:
Label the key parts of a bacterial cell
Progress Step 3:
Compare the function of electron
and light microscopes
Progress Step 2:
Explain the function of the key part of a
bacterial cell
Increasing Difficulty
Today’s Learning
Think Plant and animal cells have organelles.
Plant cells have some additional organelles to animal cells.
What does a bacterial cell look like?
How can we see bacteria and other cells so clearly?
Bacterial Cells Bacterial cells are more simple than
animal and plant cells.
They have cytoplasm, a cell membrane, a cell wall and genetic material.
Draw what you think a bacteria looks like.
This bacterial cell has a FLAGELLUM which could be used for movement or to damage other cells with.
Genomic deoxyribonucleic acid is CHROMOSOMAL DNA. It contains the biological information that is passed on from one generation to the next. It is separate from Plasmid DNA.
A plasmid is a small DNA strand that is separate from the CHROMOSOMAL DNA. Plasmid DNA is able to replicate and carries genes that may aid the survival of the organism.
For example: antibiotic resistance.
Note:
This bacterial cell has NO distinct NUCLEUS due to its lack of a nuclear membrane.
Many flagella
Bacteria don’t
always have a flagellu
m
Examiners Tip!
Bacterial cells have a cell wall and only
one circular chromosome but
no nucleus.
TASK:Draw a bacterial cell and label it
with the following key words:
Cell Membrane
Cytoplasm
PlasmidDNA
Chromosomal DNA
Cell Wall
Flagellum
Feature Animal Cell Plant/ Algal Cell
Bacterial Cell
Cell Membrane
Nucleus
Plasmids
Chloroplasts
Cell Wall
Cytoplasm
Task: Copy And Complete
Feature Animal Cell Plant/ Algal Cell
Bacterial Cell
Cell Membrane
Yes Yes Yes
Nucleus Yes Yes No
Plasmids No No Yes
Chloroplasts No Yes No
Cell Wall No Yes Yes
Cytoplasm Yes Yes Yes
Task: Copy And Complete
Simple MicroscopySeeing the bigger picture.
Light Microscope Electron Microscope
Light passes through the specimen and then through the magnifying lenses so you can see the object much bigger.
Passes a beam of electrons through the specimen to magnify it
Magnificatio
n
x1500Magnifica
tion
X2 000 000
A light microscope shows us bacteria don't have a nucleus.
An electron microscope shows us that bacteria have two types of DNA, chromosomal and plasmid DNA.
Task Complete Worksheet 2.2d.
Stick the completed sheet into your exercise book.
Try worksheet 5.4 ‘Cell Structure’.
What Are We Learning By the end of this lesson, you should:
Be able to describe the structure of a bacterial cell.
Relate the structure to the function of a bacterial cell.
Reflection: What Do You Know Now?
Bacteria
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