Chapter 2 Cell Structure and organisation Flashcards
Define nucleus
An organelle that contains genetic information.
What are the different membranes surrounding the nucleus and what are there functions?
The nucleus is bounded by two membranes : the nuclear envelope with pores that allow the passage of large molecules and the outer membrane is continuous with the endoplasmic reticulum .
What are the 3 principles of cell theory?
- All living organisms are composed of one or more cells.
- The cell is the basic unit of life.
- Cells can only arise from pre-existing cells.
What is the mitochondria?
The site of ATP production during aerobic respiration.
What are the components of the mitochondria? (3)
- The mitochondria has two membranes.
- An organic matrix containing compounds such as lipids and proteins.
- 70S ribosomes and a small circle of DNA which enable it to create proteins and to self replicate.
What is a cristae?
The inner membrane of the mitochondria which fold to provide a large surface area for the attachment of enzymes for respiration.
What is a chloroplast?
The site of photosynthesis within a cell.
What are the components of a chloroplast? (2)
- Chloroplasts are surrounded by two membranes.
* They contain 70S ribosomes and a small circle of DNA to enable self replication.
What are the stroma?
The stroma are fluid filled sacs in the chloroplasts and contains lipids and starch used for photosynthesis.
What are thylakoids?
Thylakoids are located within the stroma and are small flattened sacs which stack together to make a granum.
What is a granum and what is its function?
Granums are stacks of thylakoids and contain photosynthetic pigments such as chlorophyll.
What is the endoplasmic reticulum?
A system of double membranes which allows the transport of materials through the cell
What is the Rough ER?
An ER with ribosomes on the outer surface and transports the proteins that are made there.
What is the Smooth ER?
Membranes that lack ribosomes and is associated with the synthesis and transportation of lipids.
What is a Golgi body?
A complex of vesicles and folded membranes involved in intracellular transport.
What are the functions of the Golgi body? (5)
- produces secretory enzymes packed in the vesicles
- secretes carbohydrates
- produces glycoproteins
- transporting and storing lipids
- forming lysosomes and containing digestive enzymes.
What are lysosomes?
Small temporary vacuoles surrounded by a single membrane.
How are lysosomes formed?
Lysosomes are formed by being pinched off the Golgi body.
What are the functions of lysosomes? (2)
- They contain and isolate digestive enzymes from the cell.
* They release these enzymes when the cell needs to recycle worn out organelles.
What are Centrioles?
Centrioles are two rings of microtubules making hollow cylinders positioned at right angles to one another.
What are the functions of the centrioles? (2)
- Helps division in animal cells.
* During cell division they organise the microtubules that make the spindle that separate the chromosomes.
What is a vacuole?
Most plant cells have a large permanent vacuole which consists of cell sap and bounded by a membrane (the tonoplast). The vacuole contains glucose, amino acids, minerals, vitamins and pigments.
What is the material in the nucleus called and what is its function?
The granular material in the nucleus is nucleoplasm. It contains chromatin which is made of coils of DNA bound to protein.
What is a nucleolus and what is its function?
The nucleolus is a spherical body within the nucleus. They are the sites of formation of rRNA and ribosomes.
What are the functions of the cell wall in plant cells? (3)
- Transport
- Support the cell
- Communication between cells
What is the plasmodesmata?
Fine strands of cytoplasm that extend through the pores in plant cell walls, connecting the cytoplasm of one cell with that of another.
Give one example of how organelles are interrelated.
Protein synthesis:
Translation in nucleus, mRNA travels to ribosome for transcription, packaged at the Golgi body.
Define prokaryote and give an example.
A single celled organism lacking membrane-bound organelles , with its DNA free in the cytoplasm.
E.g bacterium.
Define eukaryote and give an example.
An organism containing cells that have membrane-bound organelles with its DNA in chromosomes within a nucleus.
What is a ribosome chemically composed of?
Ribosomal RNA (rRNA) Protein
What is the process of differential centrifugation?
Cellular material is ground up with an isotonic sucrose buffed solution over ice. The solution is spun in a centrifuge where dense organelles are separated. The remaining solution is spun at an increasingly faster speed and the less dense organelles separate and can be removed. Separating organelles is called subcellular fractionation.
Which two types of large molecules are always present in virus particles?
Nucleic acid
Protein
Define tissue
A group of cells working together with a common function, structure and origin in the embryo.
What are the 4 types of tissue?
Epithelium
Muscle
Connective
Nerve
What are the characteristics and functions of epithelial tissue?
Epithelial tissue forms a layer of cells and covers all body organs and lines all glands. The cells are formed on a basement membrane. Epithelium tissue often has protective or secretory functions.
What is a basement membrane of epithelium tissue made up of?
Collagen and protein
What are the key characteristics of simple cuboidal epithelium and give an example of where it can be found?
Cells have a cube shape and the tissue is one cell thick.
It can be found in the kidney tubules and thyroid gland.
What are the key characteristics of columnar epithelium and give an example of where it can be found?
Elongated cells with cilia.
It lines the trachea and oviducts.
What are the characteristics of Squamous epithelium and where can it be found?
Flattened cells on a basement membrane.
They form the walls of the alveoli in the lungs.
What are the 3 types of muscle tissue?
Smooth
Striated/skeletal
Cardiac
What are the characteristics of smooth muscle?
- Spindle shaped cells.
- Cells have a single nucleus.
- Involuntary control, stimulated by nerve impulses and hormones.
What are examples of where smooth muscle can be found?
The walls of blood vessels (arteries) and in the digestive tract (gut)
What are the characteristics of striated/skeletal muscles?
- Bundles of long thin cells containing proteins (actin and myosin).
- Cells are multinucleate
- Voluntary control, stimulated by nerve impulses.
Where are striated/skeletal muscle found?
Bones
Biceps
What are the characteristics of cardiac muscle?
- Myogenic (does not need a nerve impulse to trigger contraction, it is started in the muscle itself)
- Appears striated
- Cells have single nucleus
- Does not fatigue
Where is cardiac muscle found?
In the heart
What are the characteristics of connective tissue and what is its function?
It contains collagen fibres allowing it to be tough with great tensile strength but inelastic.
The function of connective tissue is to connect, support and separate tissues and organs.
Where can connective tissue be found?
Blood
Bone
Cartilage
