cells reproduction and inheritance - alva...
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Cells Reproduction and Inheritance
Cells
Cells are the tiny building blocks that make up all living things.
Living things can be unicellular or multicellular.
Unicellular = _______organism made of only 1 cell_
Multicellular = ____organism made of multiple/many cells_____
Cells are measured in µm.
1mm = _1000_ µm
The Microscope
See PPoint for completed diagram
Lens Colour Eyepiece
Magnification
Lens
Magnification
Total
Magnification
Small
Medium
Long
S2 Biology 3
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Objects viewed under a microscope look much bigger but they also look slightly
different to the actual object.
The letter P as it looks on the slide:
The letter P as you look down the eyepiece lens:
Describe the 2 differences:
1. __Upside down_______________________
2. __back to front______________________________
Make up more slides to view and draw what you see below, remember to note the
object and the magnification used.
Magnification = x _____
P
P
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Examining Cells
Animal Cell Plant Cell Bacterial Cell Yeast Cell
X _____ X_____ X______ X______
In order to be able to view cells under a microscope a stain must be added.
Cell Type Stain Used Colour of Stain
Animal methylene blue blue
Plant iodine orange/brown
Bacteria nigrosin black
Yeast methylene blue blue
Cell Structure
__yeast__ Cell __bacterial__ Cell
__plant_ Cell __animal__ Cell
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Cell Parts and Functions
Cell Part Function Found in
Nucleus
contains genetic information
Plant
Yeast
Animal
Cell Membrane
allows substances to pass into and
out of the cell
Plant
Yeast
Animal
Bacterial
Cytoplasm
site of chemical reactions
Plant
Yeast
Animal
Bacterial
Cell wall
holds plant cell shape/structure
Plant
Yeast
Bacterial
Chloroplast
site of photosynthesis
Plant
Vacuole
contains dissolved sugars/salts
Plant
Yeast
Plasmid
contains genetic information
Bacterial
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Specialised Cells
There are many different types of animal and plant cell. They are called
specialised cells and all have very different jobs.
Although all animal cells and all plant cells have the same basic parts, they can
have special features that make them good at their job.
Specialised
Cell
Plant or
Animal?
Diagram
Function How structure
makes it good at
its job
Red blood
cell
animal
carry oxygen Biconcave shape
increases surface
area
No nucleus – more
space for oxygen
Haemoglobin –
carries oxygen
Leaf
palisade
cell
plant
photosynthesis has lots of
chloroplasts for
photosynthesis
large surface area
to maximise light
absorption
Nerve cell
animal
carry electrical
messages
long and thin to
carry messages all
around body
insulated for quick
transfer of
electrical messages
Root hair
cell
plant
absorbs water large surface area
maximises water
absorption
Specialised Cells for Reproduction
In order for animals to reproduce, they must produce specialised cells called
sperm and eggs.
These specialised cells are known as sex cells or gametes.
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Male gamete = ___sperm___
Female gamete = __egg_____
The Sperm Cell The Egg Cell
Diagram
Site of production
testes ovary
Size
very small larger
Number
half a billion
1500 per second
one per month
Mobility
tail to swim cannot move independently
Fertilisation
Fertilisation is when the nucleus of an egg cell fuses with the nucleus_ of a
sperm cell.
Site of fertilisation = __oviduct_
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Only 1 sperm can fertilise an
egg cell.
The sperm cell has _50_ % of
the genetic information in its
nucleus
The egg cell has 50_ % of the
genetic information in its
nucleus
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See PPoint for completed diagrams
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Embryo Development
Stages of Fertilisation
See PPoint for completed diagram
After fertilisation the tiny ball of cells implants into the wall of the uterus and
begins to develop.
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Developing Embryo
Size _o.1mm_
Important developments:
__Cells divide and becomes a blastocyct.
Moves along oviduct____
___________________________________
Size ___0.5-0.7mm___
Important developments:
Cells implant into uterus lining
Size __3mm___
Important developments:
___arms and legs grow longer. Lungs begin to
develop_____
___________________________________
Size ___16cm__
Important developments:
baby can hear, swallow and move
around_______
Size __50cm__
Important developments:
head hair coarse, fingernails longer____
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Effect of Chemicals on Developing Embryos
Chemicals like tobacco and alcohol can have effect the growth and development
of an embryo.
Complete the graph below to show the effect of smoking on an unborn baby
Smoking Status of Mother Average weight of baby at birth (g)
Non smoker 340
Smoker who gave up before pregnancy 335
Smoker throughout pregnancy 315
Describe the effect of smoking on the average weight of babies at birth.
Smoking decreases the average birth weight of babies
___________________________________________________________
300
Ave
rage
wei
ght
of b
aby
at b
irth
(g)
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Inheritance
Genetic information is passed on from parents to their offspring (children)
through genes found on DNA. This happens during fertilisation.
Information about characteristics like hair colour, height, blood type and eye
colour are all passed on by parents. This is called inheritance.
The characteristics we can see in an organism is called its phenotype.
For every characteristic we have, we receive 2 copies of the gene that controls
this. One copy from mum and the other from dad.
Inheriting Eye Colour
The gene for eye colour can take many different forms, blue, green, brown,
hazel etc.
Mum X Dad
Blue eyes Brown eyes
Child
The child has received one gene for blue eyes from dad and one gene for brown
eyes from mum.
The child’s eyes will be __brown__
The dominant gene for eye colour is __brown__
Dominant traits are always shown in the organisms’ phenotype.
My phenotype
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Characteristics and Identification of Organisms
An organism’s phenotype can help it to be identified.
Scientists use keys for identification.
Branching Keys
A branching key is a diagram with questions that you answer and follow to
identify the organisms within it.
Use the key to identify the 2 organisms below:
____Paula__
___Tom____
Yes
Do its wings join
at the bottom?
Betsy Tom Paula Fred
Mike Scott
6 legs
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DNA Structure and Function
DNA a like special code that is found on chromosomes in the nucleus of cells.
In bacteria, the plasmid is made of DNA.
It contains many regions called genes that control an organisms characteristics.
Each gene tells your body how to make a particular protein.
DNA Profiling
DNA profiling is when the special code on a person’s DNA is collected and
analysed. It can be used for many different reasons.
Uses of DNA
DNA is unique so no one’s DNA is the same. This makes DNA very useful for
identifying certain individuals.
DNA Use Description of Use Advantages Disadvantages
Forensics
DNA sequences can be
collected as evidence
from crime scenes and
can be compared with
DNA from victims and
suspects to find a match
Identifies criminals Time consuming,
criminal’s DNA must
be on record in
order to be found a
match
Paternity Testing
DNA from parents and
children can be
sequenced and compared
to look for similarities
Identifies
biological parents
of children
Someone might not
realise that their
parents are not in
fact their biological
parents so could be
upsetting to find out
Disease
Detection
DNA of individuals can
be sequenced and
checked for sequences
that cause/could cause
certain inherited
diseases
Can allow people to
prepare for illness
or disease/can help
future and family
planning/allows
people to take
preventative
measures
Some people might
not want to know if
they are going to
develop a
disease/might
affect life insurance
or mortgages
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