Animal Biology
What is cell memrane made of?
-Mostly made up of phospholipids (preventg water passing through)
-Some protein have cabohydartes attached (glycoprotien)
-lipids with carbohydrates attached (glycolipids)
-cholesterol
Why do cells need a cell membrane?
-Controls enetery and exit of substances
-control the cell contents + organelles
-communication with external environments
-site of chemical reactions
-transport and packaging within a cell
-allows cell to change shape
The fluid mosaic model
-The phospholipid bilayer is not a fixed structure
-Although the bilayer will always remain arranged in this configuration the individual phosolipids are able to move
Phospholipid structure
-composed of a glyceral backbone, two fatty acid chains and a phosphate group
-The fatty acid chains are non-polar
-The phosphate group is polar meaning it can mix with water so it is known as hydrophilic or 'water-loving'
-The fatty acid taqil has no charge so cannot mix with water so it is hydrophobic or 'water-hating
Proteins in the membrane
-some protiens are transmembrane (they span the width of the phosophlipid bilayer)
-Others are fixed into the bilayer on one side only theses are peripheral protiens
-The proteins have several different functions
Transmembrane protiens
-Water soultuble subsatnces pass through protien channels in the bilayer
-Some channels use energy to transport substances across e.g the soduim-pottasium pump
Peripheral protiens
-Glycoproteins allow cells to communicate with one another
-Individual groups of cells have their own glycoprotiens, recognisable by the immune system
-Proteins of the cells surface also act as recivers for incoming messages
Eukaryotic and prokaryotic cells
-
Eukaryotic cells
-Has a membrane bound nucleus oand cell organelles
-Has DNA arranged in chromosomes
-E.G- plant, animal and fungi
Prokaryotic cells
-A single-celled organiam thet has no membrane bound nucleus or other organelles
-Has 2 main groups - Bacteria and archaea
-Smaller then eukaryotic cells
-can be pathogenic
Eukaryotic cell oraganelles
-
Nucleus
-Contains chromosomes (codes/controls the cell)
- enclosed by the nucleur eveolope - made up of the phospholipid bilayer which joins to endoplasmic reculum
-contains nucleur pores (act as gates)
Nucleolus
-centre of nucleus
-Transcribes RNA to send messages/ make molecules
Mitochondria
-Double membrane-bound
-Cell power plant - generates most of the energy in the form adenosine triphosphate (ATP)
-Inner folded membrane increases surface area to produce a large amount of energy
Ribosomes
-located on the rough endoplasmic reticulm and can be free floating
-made up of 2 parts (sub-units)- 1 bigger then the other
-25-30 nanometres in size
-primary sites of protein synthesis (translation)
-links amino acids together in a sequence as instructed by messenger RNA
Vacuole
-enclosed compartment filled with water and enzymes
-formed in fusion of multiple smaller vesicles
-no single-shaped varies depending on function
-isoletes harmful material
-contains waste products
-maintain a stable acidic PH
-maintains hydrostatic pressure and cell torgidity
Chloroplast
-contains chlorophhyll (makes it green)
- It contains lots of folded membranes (thylakoids)
-works with energy from the sun to produce glycose
-only fully works in daylight
smooth endoplasmic reticulm (SER)
-contains enzymes which help to synthesize lipids, oils and phospholipids
-helps produce hormones
-aids the breakdown of glycogen to glycose in the liver
-helps remove alcohol and drugs from the liver
rough endoplasmic reticulum (RER)
- contain ribosomes which give it the rough look
-helps transport proteins to the golgi body where it gets secreted
Golgi body
-modifies, sorts and packages proteins made by the ribosomes and modified by the RER
-packages protein into vesicles that can then transport the protein to where they are needed either in or out the cell
Lysomes
-contains digestive enzymes
-breaks down excess or worm out cells organelles
-viral and bacterial cells that have been engulfed and food particles
-the membrane surronding the vesicle prevents the enzymes from causing admage to the cell
Centrioles (animal only)
-cells contain two centrioles made up of microtubles
-only visible during mitosis when cell is dividing
-help move the chromosomes toward the poles of the cell
cytoskeleton
-made up of mocrotubules and microfilagments
-series of filaments and rods which help the cell keep its shape
passive transport
-requires no energy
-simple diffusion
-facilitated diffusion
-osmosis
active transport
-requires energy in form ATP
-sodium-potassiom pump
-co-transport
-exocytosis
-endocytosis (phagocytosis + pinocytosis)
simple diffusion
-movement is small, lipid soluble molecules down the concentration gradient (high to low)
facilated diffusion
-movement of ions and polar molecules across a cell membrane
-uses channel proteins
definitions
ATP- adensine triphosphate
ADP- adenosine diphosphate
Pi- phosphate ion
osmosis
-movement of water molecules from high to low
-has water surronding the cell (hypotonic)
-fluid contains less water (hypertonic)
-if the water concentration is the same it is isotonic
Active transport
-requires breakdown of atp into adp+pi to release energy
-movement of substrate against their concentration gradient (low to high)
co-transport
-some molecules join others to enter the cell (sodium + glycose)
-sodium gets actively transported into the cell
-amino acids + glycose enter alongside sodium ions
endocytosis
movement of larger molecules into a cell
phagoclytosis- cell surronds larger molecules often a cell such as bacterium
pinocytosis- cell membrane surronds droplets of fluid usally water
exocytosis
-removal of substances from a cell
-a vesicle (from golgi body) surronds the substance
-fuses with the cell membrane and the contents of the vesicle are expelled
compound microscope
-most common
-usally looks at specimens from slides
-uses light to penetratre and visualise tissue and cells
positive- easy to prepare and see what it is
negative- not much detail and limited magnification
Dissection compound
-for larger specimens
-light bounces off outer surface
positive-easy to set up and easy to use
negative- not in much detail and low resolution
scanning electron microscope (SEM)
-specimen placed in chamber
-electron beams bounce offto create 3D image
positive- very clear and has a high resolution
negative- only veiw dead specimen and its expensive
Transmission electron microscope (TEM)
-specimens thinly sliced
-High powered magnification
-electron beams pass through a specimen
positive- very clear and has a high resolution
negative- expensive and hard to prepare
calculations
microscope magnification
eye peice x objective= total magnification
image magnification
actual size= image size/magnification
Domain
-organisms are grouped based on physical characteristics
-The first rank of the system is called Domain
-There are 3 types of domain -Bacteria, archaea and Eukarya
Kingdoms
- The next rank in the system is kingdom
-There are 5 types of kingdom
-animal (all multicelluar animals)
-plant (all green plants)
-fungi (mould, mushroom and yeast)
-protist (amoeba and paramecium)
-prokaryotic (blue-green algi)
Ranks
There are several ranks
-kingdom
-phylum
-class
-order
-family
-genus
-species
-every animal is given a two part name the genus and the species
Why is latin used?
-It was the universal language
-helps identify species that look similar
-essensial for international research
-was a language used by acedemics
Natural selection
-process over time
-selects for organisms with traits best suited to environment
-individuals with adaptive traits= more likely to survive and reproduce
-adaptive traits passed to offspring
-shapes population
Evalution
-There are 2 forms of evalution
-Divergent evolution
-Convergent evolution
Phylogenetic tree
- A branchy diagram that shows how closely related all life on earth is
-Based on physical and genetically similar they are
-shows common ancestors on main branch
-the closer the branches are together the more closely related the animals are
DNA structure
-type of nucleic acid
-stores genetic material (instruction grow from fertalised egg)
-contained in nucleus
-pacaged in chromosome
-small sections of DNA have different protiens (genome)
Diploid- full
Haploid- 1/2 egg and sperm
DNA made of
-chromosome-long strand of DNA molecule
-polymer- lots of individual nucleotides joined together
-each nucleotide- phosphate group, deotyribase suger and base
four bases
-nucleotides are building blocks for DNA
-come in 4 types which are identical parts to base
-a base is known as the sub unit of DNA and MRNA
-purines- double ringed structure
-pyrimidines- single ringed structure
A-T Adeline-Thymine
C-G Cytosine-Guanine
Genetic coding
-sections of DNA codes the production of protiens
-sequence of bases within these genes is important
-every 3 bases codes for a specific amino acid (triplet code)
-amiono acid join together from peptides or polypetides (protiens)
-There are 20 different amino acids
DNA
-DNA is always double strainded
-DNA has deobi
RNA
-RNA is a single stand
-RNA has ribsome and uracil (instead of tymine)