animal cell structure

including some plant cell info too!!

what is a cell?

smallest building block in an organism and are capable of carrying out specific functions

how are cells able to carry out different functions?

differentiation

what is ultrastructure?

the internal structure of a cell as not visible on a light microscope

what are the three domains of all living things?

• archaea

• bacteria

• eukaryota

what is a cell made of (main groups)?

• proteins

• polysaccharides

• lipids

• nucleic acids

what is the significance of the proteins w/in a cell?

• enzymes in the cytoplasm and inside organelles

• associated w/ the membrane

• associated w/ DNA in the nucleus

• associated w/ RNA in ribosomes

• cytoskeleton

what is the significance of the polysaccharides w/ in a cell?

• associated w/ the membrane

• makes up cell walls

• stored for energy reserve

what is the significance of the lipids w/in a cell?

• stored for energy reserve

• phospholipids make up cell membranes

• cholesterol associated w/ membrane and controls fluidity

where are the nucleic acids w/in the cell found?

• DNA: associated w/ proteins in the nucleus

• RNA: mRNA, rRNA, tRNA - different types found in nucleus or cytoplasm or associated w/ proteins in ribosomes

what is the function of the nucleus?

• contains DNA instructions for protein synthesis

• produces mRNA and tRNA needed for protein synthesis

• nucleolus manufactures rRNA and ribosomes

what is the structure of the nucleus?

• nuclear envelope: double membrane that surrounds the nucleus (membrane bound)

• nuclear pores: allow large molecules out of the nucleus e.g. mRNA

• nucleoplasm: granular, jelly-like material

• nucleolus: small sphere w/in nucleus

• chromosomes: linear DNA that is bound to histone proteins

what is the difference between chromosomes and chromatin?

chromosomes:

• linear molecule of DNA tightly wrapped around histone proteins

• DNA is only in this form during cell division

chromatin:

• DNA more loosely associated w/ histones

• enclosed in the nucleus

what are the two types of endoplasmic reticulum (ER)?

• rough endoplasmic reticulum (RER)?

• smooth endoplasmic reticulum (SER)?

what is the structure of the RER?

• continuous w/ the nuclear membrane, membrane bound

• has ribosomes on cisternae

what is the function of the RER?

• cisternae provide large SA for protein synthesis

• protein collects inside RER and transported throughout cell

what is the structure of the SER?

• membrane bound

• no ribosomes (hence smooth)

• more tubular than RER

what is the function of the SER?

synthesises, stores and transports lipids, steroids and carbohydrates

what is the function of the ribosomes?

site of protein synthesis

what is the structure of the ribosomes?

• made up of ribosomal RNA (rRNA) and protein

• consists of a large and small subunit

• two types: 80S (found in eukaryotic cells) and 70S (found in prokaryotic cells, mitochondria and chloroplasts)

what is the structure of the Golgi apparatus?

• membrane bound

• stacks of cisternae (flattened, membrane bound sacs)

• vesicles are continuously pinched off from the ends

what is the function of the Golgi apparatus?

• proteins and lipids produced by the ER are passed through the Golgi apparatus for modification, processing, sorting and transportation

• adds carbohydrates to proteins or lipids produced in ER to form glycoproteins/glycolipids

• produce secretory enzymes

• secrete carbohydrates e.g. those used in making plant cell walls

• form lysosomes (as they are Golgi vesicles)

what events take place when a protein is made and sent to the extracellular space?

• a gene is transcribed into mRNA in the nucleus

• the mRNA leaves through a nuclear pore

• the mRNA reaches a ribosome on the RER

• the ribosome synthesises a protein into the RER

• the protein is packed in a vesicle that leaves the RER

• the vesicle reaches the golgi and fuses w/ its cisternae

• the protein is released outside

what are lysosomes?

type of Golgi vesicle containing hydrolytic enzymes (proteases, lipases, lysozymes)

what is the function of lysosomes?

digests unwanted material in the cell:

• hydrolyses material ingested by phagocytic cell

• exocytosis - releases enzymes to outside of cell to destroy material

• digests worn out organelles

• autolysis - complete breakdown of cells after they have died

what is the function of the mitochondria?

• site of aerobic respiration

• releases ATP during respiration - source of energy for cell activities

what is the structure of the mitochondria?

• double membraned (membrane bound) - inner membrane folds to form cristae, where respiratory enzymes are embedded

• fluid centre = mitochondrial matrix - also contains respiratory enzymes as well as loop of mitochondrial DNA, proteins, lipids and ribosomes