natural science

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cell biology

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eukaryotic cells

prokaryotic cells

a type of cell that have a true nucleus, DNA in nucleus and membrane-bound organelles. (bigger and more complex) e.g. plant, animal cells, fungi, protists

A type of cell that does not have a true nucleus, membrane-bound organelles and free DNA. (simpler and older) e.g. Bacteria, algae

organelles

plasms

cytoplasm- everything in the cell apart from the nucleus

cytosol- the fluid everything sits in

cytosol+organelles=cytoplasm

Protoplasm- everything in the cell including the nucleus.

nucleus

structure

function

largest organelle

chromatin (dark patches

spherical

surrounded by nuclear envelope

two fluid filed membranes

nuclear pores

contains genetic material

chromatin consists of DNA and proteins

contains instructions for making protein

nucleolus

structure

functions

located inside nucleus

makes RNA and ribosomes

Endoplasmic reticulum (SER/RER)

Structure

function

consist of flattened membrane-bound sacs - cisternae which are continuous with the outer nuclear membrane

smooth ER and rough ER

SER- involved in making carbs, lipids and steroids

RER- transport proteins made on attached ribosomes

golgi body/apparatus

structure

stack of membrane-bound flattened sacs

function

receives protein from the ER

modifies them e.g. adds sugar

packages proteins into vesicles to be transported inside cell or to the outside

mitochondria

structure

function

2 membranes separated by a fluid filled space

inner membrane is folded to form cristae

central part is the matrix

site where ATP is produced during respiration

higher concentrations in metabolically active cells e.g. muscle, liver, sperm

where most respiration reactions happen

lysosome

structure

function

spherical sacs surrounded by a single membrane

contains digestive enzymes which break down materials

e.g. specialised lysosome (acrosome) in head of sperm cells helps penetrate the egg

cell membrane

structure

function

composed of a phospholipid bilayer with embedded proteins

selectively permeable to ions and organic molecules and regulates the movement of substances in and out of cells

Centrioles

structure

function

small protein tubes of microtubules

form fibers in cell division known as spindles which separate chromosomes

ribosomes

structure

function

very small organelles in the cytoplasm and bound to rough ER

consist of 2 subunits

site of protein synthesis (the process in which cells make proteins) which acts as an assembly line to use mRNA to assemble proteins

biological molecules

Carbohydrates

living organisms need carbohydrates - to act as a source of energy e.g. sugars, starch, glycogen - to play a structural role in plant cell walls e.g. cellulose

Glucose

isomers are molecules with the same molecular formula as each other, but with the atoms connected in a different way

β glucose image

α glucose image

large chain of monomers is called a polysaccharide

plants form starch

aniamls form glycogen

valuable storage molecules that can be broken down into monosaccharides when energy is required

pair of monomers is called a disaccharide

glucose + galactose --> lactose

glucose + fructose --> sucrose

Glucose + glucose --> maltose

When combined in pairs, monosaccharides form disaccharides, forming a Glycosidic bond image

single is called a monosaccharide

image

part of nucleotides

source of energy in respiration

building blocks for polysaccharides

formula image e.g. glucose image

soluble substances

monomer is a saccharide

protein

protein structure

quaternary

two or more polypeptide chains in tertiary form combined to form complexes joined by bonds similar to those in tertiary structure

Tertiary

the folding on the alpha helix to form very specific 3D shapes, maintained by bonds

secondary: beta pleated sheet

less common. formed by hydrogen bonding between the peptide bonds in the polypeptide chain

secondary: alpha helix

most common secondary form, formed by hydrogen bonding between the peptide bonds in the polypeptide chain

primary

the type, number and sequence of amino acids in a polypeptide chain, linked by peptide bonds only

polymerization through condensation to form peptide bonds

20 different amino acids -- usually R group varies

chain of amino acids is a polypeptide (simplest form of protein)

made of amino acid monomers

image

Proteins are made of C, H and O in addition to Nitrogen.
Some can also contain sulphur and phosphorus, but always look out for the nitrogen.

nucleic acids

RNA - ribonucleic acid

image

URACIL

ADENINE

GUANINE

CYTOSINE

DNA - deoxyribonucleic acid

image

double strands

GUANINE + CYTOSINE - triple bond

ADENINE + THYMINE - double bond

made of nucleotide monomers

1 nucleotide is made from -

image

1 phosphate - up the side

1 base - up the side

1 pentose sugar - in the middle

polymers are DNA and RNA

lipids

phospholipid

'head' is the hydrophilic phosphate group

the 'tail' is the hydrophobic fatty acids

formed when 2 fatty acids and a phosphate group join to a glycerol

image

monomer is called a glycerol -- when condensation reaction occurs, ester bonds are formed to form glycerides e.g. triglycerides (3 fatty acids and 1 glycerol)

used for water proofing, insulation and protection

source of energy

contribute to the flexibility of cell membranes

made of carbon, hydrogen and oxygen plus phosphorus as phosphate in phospholipids (not in set ratio(