Cell Structures Overview

Structure of plasma membrane 

phosholipid bilayer 

hydrophobic tail and hydrophilic head 

consists of one saturated and one unsaturated fatty acid chains 

Function of the plasma membrane

controls what goes in and out of the cell

regulates the exchange of substances

maintains homeostasis

acts as a barrier for communication between cell and its environment 

What is the current model for the celllular membrane?

Fluid Mosaic Model

What is the backbone of the membrane 

Phospholipids — composed of hydrophilic head and hydrophobic tail 

Why cannot large molecules pass through the bilayer easily?

The molecules are tightly packed.

Hydrophlic molecules, although small find it harder to move due to the hydrophobic region in the middle.

Structure of nucleus

contains nuclear envelope — nuclear pores

nucleolus

nucleus

Function of the nucleus

houses the cell’s DNA

regulates gene expression

directs cellular activities

Function of the nuclear envelope

allows substances such as mRNA to leave the nucleus

Function of the nucleolus

contains chromatin

site of ribosomal synthesis and rRNA

Function of ribosomes 

transport and produce proteins — protein synthesis 

Two types of ribosomes

Free and bound

where are free ribosomes found? and where are they used?

in the cytoplasm

used in solution in cytoplasm

where are bound ribosomes found and what are they used for? 

found in rough  endoplasmic reticulum 

used in vesicles 

Function of endoplasmic reticulum

network of membranes involved in synthesis and transport of proteins throughout the internal region of the cell

Function of smooth ER

makes lipids, phospholipids

transportation of lipid based compounds 

detoxification of drugs in the liver 

production of sex hormones 

Function of rough ER 

engages in protein development and transport 

Function of vesicles

membrane bound sacs that contain and transport materials within the cell

Types of vesicles

Transport vesicles

Secretory vesicles

Function of transport vesicles 

move substances between locations inside the cell by budding off one organelle compartment and fusing with another 

Function of secretory vesicles

secrete molecules out of the cells via exocytosis

Function of lysosome

break down many types of biomolecules

fuse with old or damaged organelles in order to break them down

structure of Golgi Apparatus 

consists of flattened sacs called cisternae 

stacked one top of each other f

function of golgi apparatus

collection, packaging and modification of materials synthesized in the cell

structure of mitochondria 

rod shaped organelles

double membrane — inner membrane is folded inwards to form a cristae 

contains a semi fluid called the matrix 

structure of mitochondria

site of aerobic respiration and ATP synthesis

structure of cristae

provides a huge surface are within which chemica reactions occur

structure of chloroplast

contains a double membrane

same size as bacterial cell

contains own DNA and 70s ribosomes

grana

thylakoids

stroma

Function of the chloroplast 

phorosynthetic pigments such as chlorophyll found in thylakoids 

Responsible for biosynthesis of active compounds like amino acids 

Function of the granum

consists of 2-100 closed parallel flattened sacs

provides a large surface area for trapping light f

function of thylakoid

flattened membrane sacs containing photosynthetic pigments to trap light energy in order to power photosynthesis

function of stroma 

fluid filled contains some products of photosynthesis