cell structure and function

Question 1

the nucleus

Answer 1

storage and utilisation of DNA
surrounded by double membrane
most prominent organelle
contains dna packaged into chromosomes
membrane links to endoplasmic reticulum
contains specialised structures called nucleoli

Question 2

the mitochondrion

Answer 2

generates most of the cells ATP
surrounded by double membrane
highly folded inner membrane
contains its own DNA
reproduces by splitting into two
site of cellular respiration - Krebs cycle and ETC
the outer membrane contains porins which form channels that allow molecules of 5000 Da or less to freely diffuse from one side of the membrane to the other
>the inner mitochondrial membrane contains proteins that :
*perform the redox reactions of oxidative phosphorylation
*atp synthase , which generates ATP in the matrix
*specific transport proteins that regulate metabolite passage into and out of the matrix
cristae expand the surface area of the inner mitochondrial membrane enhancing its ability to produce ATP
matrix Is the site of the Krebs cycle

Question 3

mitochondrial DNA

Answer 3

mtDNA is inherited solely from the mother
circular , covalently closed , double stranded DNA
mitochondria must be duplicated during the cell cycle and segregated to the daughter cells
number of mitochondria varies with cell type

Question 4

endoplasmic reticulum

Answer 4

synthesis of new membrane and protein
an interconnected network of flattened membrane enclosed sacs or tube like structure known as cisternae
linked to nuclear membrane
2 types- smooth and rough
rough studded with ribosomes

Question 5

what does smooth e.r and rough e.r do

Answer 5

RER- protein synthesis
SER- lipid synthesis

Question 6

ribosomes

Answer 6

site of mRNA translation and protein synthesis
made from complexes of RNAs and proteins
are not surrounded by a membrane
each ribosome is divided into two subunits
*smaller subunit which binds to a larger subunit and the mRNA transcript
*a larger subunit which binds to the tRNA , the amino acids and the smaller subunit

Question 7

Golgi body

Answer 7

sorting , modifying and packaging proteins and lipids
forms a dynamic system of membrane stacks
proteins synthesised in the ER are packaged into vesicles
Fuse with the Golgi at the cis face
these cargo proteins are modified as they progress towards the trans face
bud off as vesicles destined for secretion via exocytosis or for use in the cell
lysosomes are produced this way

Question 8

lysosomes

Answer 8

degradation of unwanted material
small and irregularly shaped
low internal PH
full of enzymes which degrade unwanted molecules
fuse with endoscopes/phagosomes and dispense their enzymes into the endoscope/phagosome , digesting their contents

Question 9

cytosol

Answer 9

that part of the cell which is not contained in any membrane bounded compartment
the liquid matrix around the organelles
cytoplasm= cytosol + organelles
cytoplasm does not include nucleus
site of glycolysis

Question 10

cytoskeleton

Answer 10

a complex network of interlinking filaments and tubules that extend throughout the cytoplasm from the nucleus to the plasma membrane
provides a framework for support giving the cell shape and mechanical resistance to deformation
it can also actively contract , thereby deforming the cell and the cell’s environment and allowing cells to migrate
it segregates chromosomes during cellular division
involved in cytokinesis