Cell membrane in animals is composed mainly of the molecule of
lipids
proteins
lipids and proteins
carbohydrates
A student wishes to study the cell structure under a light microscope having 10X eyepiece and 45X objective. He should illuminate the object by which one of the following colours of light so as to get the best possible resolution?
Yellow
Green
Blue
Red
Which one is single membrane cell organelle
Endoplasmic reticulam
Mitochondria
Lysosomes
Chloroplast
Centromere is required for
transcription
crossing over
cytoplasmic cleavage
movement of chromosomes towards poles
Protein synthesis in an animal cell occurs
only on the ribosomes present in cytosol
on ribosomes present in cytoplasm as well as in mitochondria
only on ribosomes attached to the nuclear envelope and endoplasmic reticulum
on ribosomes present in the nucleolus as well as in cytoplasm
The main organelle involved in modification and routing of newly synthesized proteins to their destinations is
mitochondria
endoplasmic reticulum
lysosome
chloroplast
B.
endoplasmic reticulum
Endoplasmic Reticulum (ER) was coined by Porter. It is a network of tubules, vesicles and cisternae within an eukaryotic cell. Two types of ER are recognised on the basis of presence or absence of ribosomes on the wall of ER:
(i) Smooth ER- It helps in the synthesis of lipid and glycogen. Wall does not contain ribosomes.
(ii) Rough ER- It helps in protein synthesis and transfer. Wall contains ribosomes.
Protein synthesis takes place in ribosomes attached on wall of ER. Newly formed protein enters within the cavity of rough ER and follows following path:
Protein Cavity of rough ER Cavity of smooth ER Golgi membrane Lysosomes or transport vesicles or secretory granules.
Arachidonic acid is
non-essential fatty acid
essential fatty acid
poly unsaturated fatty acid
both 'b' and 'c'