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B5 Revision. Growth and Development. An accelerated revision resource A.Blackford. Revision IS important. WARNING This PowerPoint is not a substitute for active revision using notes, the workbook and revision guide. You also need to do plenty of past papers to get exam practice.

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B5 revision l.jpg

B5 Revision

Growth and Development

An accelerated revision resource

A.Blackford


Revision is important l.jpg
Revision IS important

WARNING

This PowerPoint is not a substitute for active revision using notes, the workbook and revision guide.

You also need to do plenty of past papers to get exam practice.

Good luck!


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Growing and Changing

  • We develop as we grow older

  • Larger animals and plants are built of specialist cells arranged in particular ways

    You need to be able to name examples in each category for animals and plants

Cells

Tissues

Organs

Systems

Organisms

Red blood cells

Nerve cells

Palisade cells

Xylem cells

Phloem cells

Xylem tissues

Muscle tissue

Nervous tissue

Blood

Flower

Biceps muscle

Eye

Leaf

Root

Lungs

Root system

Respiratory

Skeletal

Nervous

Digestive

reproductive

Buttercup

House fly

Human

Cat

Dolphin

Earthworm

Oak tree


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Single Cell to Fully Grown

  • Human fertilised egg cells are called ZYGOTES

  • After 10 days the zygote has 100 cells

  • After 2 months the major organs have formed

  • An adult human has about 1014 cells

  • In plants, growth is at the tips of roots and shoots in areas called MERISTEMS. There are also meristems to make the stems thicker and in side buds for when they grow


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Growing Back

  • Plant meristem cells are unspecialised and can continue to grow throughout the plants lifetime.

  • Newts have spare unspecialised stem cells to allow them to grow back damaged or lost parts.

  • Human stem cells are specialised e.g. for skin.

  • Plants can be grown by using their meristems e.g. from cuttings. These are dipped in hormone rooting powder containing AUXINS to aid root growth. The new plants are clones.


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Nucleus Revision

  • Humans have 46 chromosomes (23 pairs one set from mother one set from father)

  • Human sex cells have 23 chromosomes

  • Humans have about 30 000 genes

  • Genes code for PROTEINS

  • DNA can make an exact copy of itself

  • Human red blood cells have no nucleus

DNA


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Mitosis – For growth and repair

Interphase

DNA divides

Cell grows

Organelles divide

I

Prefer

My

Aardvark

Toasted

Prophase

Chromosomes has identical copy attached to it

Chromosomes become visible

Metaphase

Chromosomes line up in the equator

Anaphase

Chromosome copies separate

Copies move to opposite ends of the cell

Telophase

New nuclear membranes form

Cytoplasm divides

2 identical cells produced (also identical to parent cell)


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Sexual Reproduction

  • Involves the fusion of male and female gametes (sex cells)

  • From any individual, no two gametes are the same. The chromosomes they have are a mixture of maternal and paternal ones

  • Gametes have HALF the number of chromosomes that the rest of the body has

  • Gametes are made by MEIOSIS which halves the number of chromosomes.


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DNA Structure

  • It has a DOUBLE HELIX structure

  • There are 4 bases that always pair up in the same way (base pairing)

  • Adenosine (A) with Thymine (T)

  • Guanine (G) with Cytosine (C)

  • It can make an exact copy of itself

    • Weak bonds between the bases split

    • A new strand starts to form on the free bases


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Making Proteins

  • Proteins are made up of amino acids

  • There are about 20 possible amino acids to use

  • 3 bases on the DNA code for a single amino acid (triplet code)

  • mRNA forms on the untwisted DNA

  • mRNA has Uracil (U) instead of thymine (T)

  • mRNA moves out of the nucleus through pores

  • Ribosomes attach to one end of the mRNA and as they move along amino acids are added to make up the protein


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Specialised Proteins

  • We have around 300 different specialised cells

  • Genes are lengths of DNA and they make proteins

Protein

Found in

Property

Strong and insoluble

Nails, hair skin

Keratin

Skin

Springy

Elastin

Tough but not very stretchy

Skin

Collagen

Speed up chemical reactions

All cells, the gut

Enzymes

Defend against disease

Antibodies

In the blood


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Gene Switching

  • The one-gene-one-protein theory

  • 25 000 – 30 000 genes in humans

  • In stem cells all these genes are switched on

  • As some cells specialise some are switched off

  • In the mammalian egg cells proteins are unevenly distributed therefore one part will become the head and the other the tail


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Stem Cells

  • Stem cells produced could be used to treat heart disease, diabetes, Parkinson’s and lots more


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Phototropism

  • Plant stems will grow towards the light. This is PHOTOTROPISM

Plants grown in normal light. Green and sturdy

Plants growing towards the light

Plants grown in the dark. They are CHLOROTIC (yellow) and spindly (ETIOLATED


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Auxins at Work

  • More auxin goes to the dark side

  • Auxin makes the cells grow faster

LIGHT

LIGHT

LIGHT

  • Conclusion

    • Auxin is produced by the tip of the oat seedling


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