Organisation + Movement into and out of cells + Biological molecules + Enzymes

cell, tissue, organ, organ system

cell - basic functional & structural units of a living organism

tissue - group of cells with similar structures working together to perform a shared function

organs - made of different tissues working together to perform specific functions

organ system - groups of organs with related functions, working together to perform body functions

organelles of an animal cell

nucleus - contains genetic material and controls cell functions

mitochondria - place where aerobic respiration takes place in a cell

cytoplasm - where anaerobic respiration takes place. jelly like substance. site of most chemical reactions in the cell

ribosome - place where protein synthesis takes place

cell membrane - separates cell from surroundings. controls movement of substances in and out of the cell. keeps content of cells inside

plant cell organelles (extra)

• cell wall -made of cellulose and gives support to the plant cell and is rigid and inelastic.

• chloroplast -contains the green pigment chlorophyll. it is the place where photosynthesis takes places. absorbs light energy for photosynthesis. chlorophyll transfers energy from light into energy in chemicals, for the synthesis of carbohydrates

• permanent vacuole - contains cell sap and is used for storage of water & mineral ions. also helps support cell shape by exerting a pressure

similarities between plant and animal cells

both have cytoplasm, nucleus, cell membrane.

differences between plant cells and animal cells

* plant cells have a cell wall, animal cells do not
* plant cells often have chloroplasts, animal cells do not
* plant cells have a regular shape, whilst animal cells are often in irregular shape
* plant cells often have large vacuoles, animal cells only have small vacuoles

how are new cells made

by division of existing cells

specialized cells

ciliated cells – movement of mucus in the

trachea and bronchi

(b) root hair cells – absorption

(c) palisade mesophyll cells – photosynthesis

(d) neurones – conduction of electrical impulses

(e) red blood cells – transport of oxygen

(f) sperm and egg cells (gametes) – reproduction

where r the specialized cells we mentioned found?

ciliated cells - lining of trachea and bronchi

root hair cells - near the ends of plant roots

xylem vessel cells - in the stems, roots, and leaves

palisade mesophyll cells - underneath the epidermis of the leaf

nerve cells - throughout the bodies of animals

red blood cells - the blood vessels of animals

sperms and eggs - testes and ovaries

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magnification formula

formula used to calculate magnification: Magnification = Image size / Object size.

mm to micrometre. 1mm = 1000 micrometres. so x1000

diffusion

the net movement of particles from a region of their higher concentration to a region of their lower concentration (i.e. down a concentration gradient), as a result of their random movement

where does the energy for diffusion come from

the kinetic energy of random movement of molecules and ions

factors that influence diffusion

• surface area - the larger the SA, the higher the rate of diffusion. cuz more molecules at a given time will be diffusing

• temperature - the higher the temp, the higher the rate of diffusion. this is because molecules move faster and have higher kinetic energy

• concentration gradient - the higher the concentration gradient, the faster the rate of diffusion

• Distance - the shorter the distance, the quicker the rate of diffusion. The shorter the distance particles must diffuse and move across, the faster diffusion is going to be.

osmosis

osmosis as the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane

what is meant by partially permeable

it will let some molecules through, but not others

roles of water in organisms

transport, digestion, excretion

Water is the universal solvent, many substances dissolve in it.

what happens when add a cell to a dilute solution AKA hypotonic solution

there is a higher water potential outside the cell, than inside the cell. this means water will move inside the cell. as water enters the cell, the cell becomes turgid (swells) until eventually the strain is too much and the cell burst. lysis occurs

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a plant cell does not burst, for it has a cell wall. (the cell wall is fully permeable btw)

what happens when you add a cell to a concentrated solution AKA hypertonic

the cells shrink and become flaccid.

plasmolysed

When plant cells are placed in a **concentrated** solution, water molecules will move **out of the plant cells by osmosis**, making them flaccid. Cytoplasm decreases in size. Cell membrane pulls away from the cell wall.

plants are supported by?

pressure exerted by a fluid in a cell that presses the cell membrane against the cell wall - turgor pressure

role of water in plants

water is important because it transport mineral ions and nitrate ions.

the water maintains the turgidity of the cell

prevent wilting

medium for enzyme action

active transport

the movement of

particles through a cell membrane from a region

of lower concentration to a region of higher

concentration (i.e. against a concentration

gradient), using energy from respiration

what moves ions during AT

protein carriers move molecules or ions across a membrane during active transport

Importance of diffusion and active transport

Diffusion: Gas exchange for respiration, removal of waste products such as CO2.

Active Transport: Uptake of glucose in villi and kidney tubules in nephron. Uptake of ions from soil.

3 main organic molecules (called organic for they contain carbon)

* carbohydrates
* fats
* protein

carbohydrate composition

carbon, hydrogen oxygen

protein composition

carbon, hydrogen, nitrogen, oxygen

fat composition

carbon, hydrogen, oxygen

what are carbohydrates, proteins and lipids made up of?

Glucose, glycogen and cellulose are made from glucose

Proteins are made from amino acids.

Fats and oil are made of fatty acids and glycerol. One glycerol molecule is chemically bonded with three fatty acid chains.

structure of DNA

two strands coiled together to form a double helix

(b) each strand contains chemicals called bases

(c) bonds between pairs of bases hold the strands together

(d) the bases always pair up in the same way: A with T (adenine and thymine), and C with G (cytosine and guanine)

catalyst

substance that increases the rate of a chem reactions and is not changed by the reaction itself

enzyme

proteins that are involved in all metabolic reactions, where they function as biological catalysts

lock & key theory

substrate fits into enzyme

because shape of substrate is complementary to the enzyme’s active site

this forms an enzyme-substrate complex

products are formed and substrate leaves enzyme

enzyme remains unchanged

how does temperature affect enzyme active

As temperature rises, the rate of enzyme activity increases. Molecules (including enzymes) have more kinetic energy and move faster. More collisions between enzyme and substrate per second/frequency of effective collisions increases.

how does an enzyme get denatured

If the temperature is too high, enzymes denature. The active site changes shape. This prevents binding of substrate/substrate can no longer fit into enzyme's active site.

how does pH affect enzyme activity

enzymes work best a particular pH. some enzymes work best in low pHs such as pepsin in the stomach. if the pH gets too acidic or too alkaline then the enzyme can get denatured.

why r enzymes important?

Enzymes reduce the activation energy of a reaction.

The increase the rate of a chemical/metabolic reaction.

The reaction can occur at lower temperatures.

Enzymes are biological catalysts.

Without enzymes reactions occur too slowly.

They provide their active site for the reaction.