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