B5 Revision Growth and Development An accelerated revision resource A.Blackford.

B5 Revision

Growth and Development

An accelerated revision resource

A.Blackford

Revision IS important

WARNINGThis 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!

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

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

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.

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

DNADNA

Mitosis – For growth and repairInterphase

DNA dividesCell growsOrganelles divide

ProphaseChromosomes has identical copy attached to itChromosomes become visible

MetaphaseChromosomes line up in the equator

AnaphaseChromosome copies separateCopies move to opposite ends of the cell

TelophaseNew nuclear membranes formCytoplasm divides2 identical cells produced (also identical to parent cell)

I

Prefer

My

Aardvark

Toasted

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.

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

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

Specialised Proteins

• We have around 300 different specialised cells• Genes are lengths of DNA and they make proteins

Antibodies

Protein Found in Property

KeratinStrong and insoluble

Elastin Skin Springy

Nails, hair skin

Tough but not very stretchy

SkinCollagen

Enzymes All cells, the gut Speed up chemical reactions

Antibodies In the blood Defend against disease

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

Stem Cells

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

Phototropism

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

Plants growing towards the light

Plants grown in normal light. Green and sturdy

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

Auxins at Work

• More auxin goes to the dark side

• Auxin makes the cells grow faster

LIGHTLIGHT

• Conclusion– Auxin is produced

by the tip of the oat seedling

LIGH

TLIG

HT

LIGHTLIGHT