cell (eukaryotes)

eukaryotic cell

have variety of complex locomotory and cytoskeletal structures. Their genetic material is organised into chromosomes

types of eukaryotic cells

plant cell, animal cell

cell membrane

composed of lipids and proteins. majorly of phospholipids arranged in bilayer

structure of lipids

polar head towards outside and hydrophobic tails inside

reason for the structure of lipids

protects the non polar tail from aqueous environment

human erthrocytes

52% proteins 40% lipids

types of proteins (basis of ease of extraction)

peripheral, integral

fluid mosaic model

proposed by singer and nikolson in 1972. it said that the quasi fluid nature of lipids allows the lateral movement of proteins across the overall bilayer

Fluidity

ability to move within the membrane

ratio of protein and lipid

varies in different cells

importance of fluid nature of membrane

for function like cell growth, formation of intercellular junctions, secretion, endocytosis, cell division etc

function of cell membrane

transport of substances

passive transport

movement without energy utilization. neutral solution move by simple diffusion along conc gradient

osmosis

movement of water through diffusion

carrier proteins why important

polar molecules cannot pass through non polar bilipid layer they require carrier proteins to facilitate the transport

active transport

energy dependent processes where molecules are transported against the conc gradient. ex na+ / k+ pump

cell wall

outer covering for plasma membrane gives shape , protection against mechanical damage an infection, helps in cell to cell interaction an serves as barrier to undesirable macromolecules

algae cell wall

mae of cellulose, galactans, mannans and minerals like caco3

cell wall in other plants made of

cellulose, hemicellulose, pectin an proteins

primary and secondary cell wall

a young plant cell has a primary cell wall capable of growth, as cell matures a secondary cell wall forms below primary cell wall closer to cell membrane

middle lamellae

between 2 plant cells there is a layer called middle lamellae made of calcium pectate which holds the neighboring cells together

plasmodesmata

tiny channels which pass through the middle lamellae and cell wall which helps to connect cytoplasm

endomembrane system

organelles considered together because their functions are coordinated. the es includes lysosomes, vacuoles, er and golgi complex