Cell structure Flashcards
State the 3 primary points of classical cell theory
Cells are the fundamental units of structure and function in living organisms.
Cells arise from pre-existing cells by division.
Explain what “magnification” and “resolution” mean
Magnification: The degree to which the viewed image is larger than the specimen.
Resolution: The minimum distance at which two points can be distinguished as separate
Explain why some organelles can only be seen with electron microscopes but not light microscopes.
Electron microscopes have a smaller resolution than light microscopes which allows it to
distinguish organelles
Outline the process and principle of cell fractionation
Cells are homogenised in a blender which disrupts the cell walls and cell membranes
and a centrifuge separates organelles based on their size Or density.
Describe the structure of the nucleus, including its contents and function
The nucleus is encased by a double membrane called the nuclear envelope.
It has a nucleolus which is an area of highly concentrated DNA, rRNA and proteins. It contains the hereditary material in the form of DNA of an organism as well as controls cellular activities
by regulating protein synthesis.
ALSO NUCLEOLUS: site of synthesis of ribosomal RNA and assembly of rRNA and ribosomal
Proteins into ribosomal subunits
Explain the role of the nuclear envelope.
The nuclear envelope is perforated by numerous nuclear pores which regulate the passage of substances in and out of the nucleus such as mRNA and ribosomal subunits
Explain the relationship between the nucleolus and the ribosomes
The nucleolus is the site of synthesis of ribosomal RNA, a component of ribosomes. (Euchromatin
Does that) and also the site of assembly of rRNA and ribosomal proteins into ribosomal subunits
Describe the structure of ribosomes.
Consists of a small subunit and a large subunit, each made of ribosomal RNA and proteins.
Ribosomes can be floating freely in the cytosol (free ribosomes) or bound to the RER (bound ribos)
Structure and functions of rough endoplasmic reticulum
Made of flattened cisternae and studded with bound ribosomes. Site of synthesis of
Proteins fold into their native 3D conformation as they enter cisternal space. Proteins synthesised
in ribosomes Undergo glycosylation to become glycoproteins and then are transported to the
Golgi apparatus by being packaged into vesicles
Structure and functions of smooth endoplasmic reticulum
Tubular cisternae and smooth. Site of synthesis of lipids and steroids like hormones.
Also detoxifies drugs and poison in liver cells.
Stores Ca2+ ions in muscles
Structure and functions of Golgi apparatus
Newly synthesised polypeptides from the rough endoplasmic reticulum are packaged into vesicles and fuse with the cis face of the Golgi apparatus, where they undergo modification or further glycosylation, after which they bud off the trans face of the Golgi apparatus in vesicles.
Golgi apparatus sorts and targets completed materials to different parts of the cell or for secretion out of the cell via secretory vesicles.
Structure and functions of lysosomes
Contains hydrolytic enzymes that digest waste products, foreign particles,
hydrolyses food and digest old organelles (autophagy)
Structure and functions of cell surface membrane
Acts as a selectively permeable barrier across which all substances entering and leaving the cell must pass through
Structure and functions of mitochondrion
Has a double membrane, the mitochondrial matrix where outer membrane is smooth
And inner membrane is highly infolded also called cristae which increases surface area to volume ratio.
The site of aerobic respiration where it converts glucose and oxygen to carbon dioxide and water
Through metabolic processes to generate energy in the form of adenosine triphosphate (ATP)
Structure and functions of chloroplast
Has double membrane and is the site of photosynthesis where carbon dioxide
And water are converted to carbohydrates and oxygen using light energy
