Cells Flashcards
What is the function of the nucleus?
contains the hereditary material and regulates cell activities
What is the function of the nuclear envelope?
a double membrane that surrounds the nucleus controlling the movement of genetic material
What is the function of nuclear pores?
allows passage of large molecules
What is the nucleoplasm?
granular jelly-like material that suspends the nucleus bound structures
What are chromosomes?
protein-bound linear DNA
What is a chromatin?
a specific section of a chromosome
What are histones?
proteins
What is the nucleolus?
it manufactures ribosomal RNA and assembles the ribosomes
What is the mitochondria?
produces ATP through aerobic respiration
What is the function of the double membrane? (mitochondria)
outer- controls entry and exit of material
inner- folded to form cristae
What is the cristae? (mitochondria)
inner membrane extensions increasing the surface area for enzymes and proteins
What is the matrix? (mitochondria)
remainder of the mitochondrion containing proteins, lipids, ribosomes and DNA
What is the chloroplast?
disc shaped organelle that carries out photosynthesis
What is the function of the envelope (chloroplast)
selectively permeable double plasma membrane surrounding the organelle
What is the function of the grana? (chloroplast)
stacks of thylakoids containing chlorophyll and first stage of photosynthesis occurs here
What is the function of the stroma? (chloroplast)
fluid filled matrix where the second stage of photosynthesis occurs
What is the endoplasmic reticulum?
sheet like membranes spreading throughout the cytoplasm enclosing a network of tubules and flattened sacs called cisternae
What is the function of the rough endoplasmic reticulum?
large surface area for ribosomal synthesis of proteins and glycoproteins- provides a pathway for protein transport
What is the function of the smooth endoplasmic reticulum?
lacks ribosomes and is tubular in appearance- synthesis, storage and transport of lipids and carbohydrates
What is the function of the Golgi apparatus?
a stack of flattened sacs with vesicles- proteins and lipids produced by the endoplasmic reticulum are modified here
What are lysosomes?
isolate the enzymes from the rest of the cell before releasing them outside or into a phagocytic vesicle
What is the function of cellulose in the cell wall?
microfibrils provide considerable strength
What is the difference between the structure of fungi and algae?
algae- cellulose and glycoproteins
fungi- no cellulose, polysaccharide chitin and glycan as glycoproteins
What is the vacuole?
contains a solution of mineral salts, sugars, amino acids, wastes and anthocyanins
What are the uses of the vacuole?
-turgidity to herbaceous plants
-food store
-attraction for pollination
What organelles are in a prokaryotic cell?
-plasma membrane
-cell wall
-capsule
-cytoplasm
-cilia
-nucleoid
-ribosomes
-plasmid
-flagellum
Describe the structure of a prokaryotic cell wall
-made from peptidoglycan (murein)
-it is a complex polymer formed from amino acids and sugars
What are the three stages of the cell cycle?
interphase, cell division, cytokinesis
What happens during interphase?
cell grows and organelles divide, dna is duplicated and more proteins and organelles are made
What happens during cell division?
nucleus divides into two (mitosis) or four (meiosis)
What happens during cytokinesis?
cytoplasm divides to produce two (mitosis) or four (meiosis) daughter cells
Describe the process of mitosis
prophase- the chromosomes become visible and the nuclear envelope disappears
metaphase- the chromosomes arrange themselves at the centre of the cell
anaphase- each of the two threads of of a chromosome migrates to an opposite pole
telophase- the nuclear envelope reforms
Describe the process of binary fission
- circular DNA and plasmids replicate and both copies attach to the cell membrane
- cell membrane begins to grow between the two molecules of DNA dividing the cell into two genetically identical daughter cells
- a new cell wall forms
What is a virus?
an acellular non-living particle
Describe the structure of viruses
they contain nucleic acids enclosed within a capsid and divide inside a living host cell, some viruses also have a lipid envelope
Do viruses go through cell division?
no, instead they attach to proteins on a cell’s surface, inject their nucleic acid which provides instructions for the cell
What is the function of the cell surface membrane?
it allows different conditions to be established inside and outside a cell and controls the movement of substances in and out
What is the name of the structure of molecules in a cell-surface membrane?
fluid mosaic model
What is the fluid mosaic?
‘fluid’ refers to the molecules moving relatively to eachother
‘mosaic’ refers to each of the different molecules in the membrane
What are the components of the plasma membrane?
phospholipids, proteins, carbohydrates
What are the uses of cholesterol?
- reduces fluidity
- less permeable to small water-soluble molecules
- separates tails to prevent crystallisation
- helps anchor peripheral proteins
- helps with temperature changes
- prevents leakage at high temperatures
What happens when a chemical binds to a carrier protein?
the protein changes shape
What is the function of a channel protein?
water filled- allows water-soluble ions/small substances
What is the use of a peripheral protein?
mechanical support
What is the definition of a passive process?
the energy required comes from the natural motion of particles rather than an external source
What is the definition of an active process?
the energy required comes from an external source such as ATP
