Animals cells Flashcards
What is metabolism in cells?
Synthesis and breaking down of molecules
Why is the nucleus in a nuclear envelope?
Double membrane; keep it away from damage in the cytoplasm; contains nuclear pores - allow molecules to move in & out of the nucleus
Why does DNA associate with the protein ‘Histones’?
To form chromatin; it coils and condenses to form chromosomes
What is the nucleolus composed of?
Proteins and RNA. RNA is used to produce ribosomal RNA (rRNA)
Where is energy stored?
Bonds of complex molecules (ATP)
Structure of Mitochondria?
Double membrane; inner one folded (cristae) & huid interior = matrix; membrane contains enzymes for aerobic respiration; has a little bit of own DNA (mtDNA)
Structure of Vesicle?
Single membrane with fluid inside
What enzymes do lysosomes have?
Hydrolytic enzymes (for immune system)
Microtubules structure and function?
Globular tubulin proteins polymerise to form tubes; acts as tracks for organelle movement; Makes spindle fibres
Microfilaments structure and function?
Formed from protein actin; cell movement and cell contraction during cytokinesis
What are intermediate fibres used for?
Give mechanical strength and help maintain the cells integrity
What forms centrosomes?
Two centrioles (no centrioles in flowering plants and fungi)
What is the flagella used for?
Cell mobility; in some cells used for sensing
Cilia function and structure?
On the surface of cells (sensory); Beat in a rhythmic manner-current (trachea). Each ciliam has 2 central microtubules surrounded by 9 pairs of microtubules (9 + 2 arrangement)
What is the endoplasmic reticulum?
Network of membranes enclosing flattened sacs (cisternae) connected to the outer membrane of the nucleus
Function of Smooth ER and Rough ER?
Smooth ER= Lipid and carbohydrate synthesis and storage
Rough ER= Ribosomes bound to surface and responsible for protein synthesis and transport
Golgi apparatus structure?
Compact structure of cisternae, no ribosomes. Packaging into vesicles or lysosomes
What is the process of protein synthesis?
(1) mRNA is transported from the nucleus to the rough ER
(2) Proteins are synthesised on ribosomes on rough ER
(3) Proteins are packaged into transport vesicles
(4) Vesicle moves to golgi via cytoskeleton
(5) Vesicle fuses with cis face of the golgi and proteins enter
(6) Proteins are modified before leaving golgi from trans face
(7) Secretory vesicles carry proteins to cell surface membrane and fuse with it, releasing their contents (exocytosis)
