Topic 2

• what is a eukaryotic cell

  larger more complex cell with a membrane bound nucleus
• what are the 9 aspects of an animal cell

  - cell surface membrane

  - SER

  - RER

  - Golgi apparatus

  - lysosomes

  - nucleus

  - ribosomes

  - mitochondria

  - centrioles
• what is the nucleus structure

  - spherical/prominent, contains:

  - RER

  - nucleolus

  - chromatin

  - nucleoplasm

  - nuclear pore

  - nuclear envelope

  
• what is the function of the nucleus

  - control centre of the cell through control of protein synthesis

  - retains genetic info (DNA) within nuclear envelope

  - allows mRNA to travel to cytoplasm through nuclear pores

  - nucleolus manufactures rRNA and assembles the ribosomes
• what is the structure of mitochondria

  - rod shaped

  - outer and inner membrane - inner = highly folded to form cristae (increase SA)

  - inter-membrane space

  - matrix: fluid inside

  - loose DNA, small ribosomes (70S), proteins, lipids and enzymes

  
• what is the function of mitochondria

  - self replicating

  - function = ATP production, site of the aerobic phase of respiration

  - large numbers in metabolically active cells
• RER structure

  - extensive membrane system of cisternae (flattened sacs), this is continuous with nuclear membrane

  - membranes are covered in ribosomes; site of protein synthesis

  
• RER function

  - large surface area for protein synthesis and synthesis of glycoproteins

  - acts as a transport system for products of protein synthesis
• what is the structure of SER

  - smooth appearance

  - extensive membrane of cisternae (flattened sacs) but is NOT covered in ribosomes

  
• what is the function of SER

  - synthesises, stores and transports lipids and carbohydrates
• what is the structure of the Golgi apparatus

  - a stack of membranes that make up cisternae - similar to SER but more compact

  - contains vesicles; small, round hollow structures

  
• what is the function of the Golgi apparatus

  modification and packaging of the products of RER and SER:

  - forms glycoproteins; adds carbohydrates to proteins

  - produces secretory enzymes

  - secretes carbohydrates

  - transports, modifies and stores lipids

  - forms lysosomes
• what is the structure of lysosomes

  - formed from vesicles produced by Golgi

  - contain hydrolytic enzymes; proteases, lipases and lysozyme

  
• what is the function of lysosomes

  - hydrolysing material ingested by phagocytosis

  - exocytosis to release enzymes out of cell

  - digests worn out organelles to recycle contents

  - breaks down dead cells
• what is the structure of ribosomes

  2 types:

  - 80s = eukaryotic cells

  - 70S = prokaryotic cells, mitochondria and chloroplasts

  - consists of 2 subunits, 1 large, 1 small

  - made from rRNA and protein

  - loose in cytoplasm or bound to ER to form RER

  
• what is the function of ribosomes

  - the site of protein synthesis
• what do plant cells contain

  all the aspects found in an animal cell, as well as:

  - tonoplast

  - chloroplast

  - cellulose wall

  - cell vacuole
• what is the structure of chloroplasts

  in plant and green algal cells:

  - outer and inner membrane/envelope

  - stroma; fluid filled centre

  - inside stroma: thylakoids (parallel flattened sacs of membrane) which are stacked to form the grana

  - chlorophyll: found inside thylakoids

  - lamella: in between grana and membranes

  - small amount of loose DNA, small ribosomes 70S and starch grains

  
• what is the function of chloroplasts

  - self replicating

  - harvest sunlight and carry out photosyntheiss
• what is the structure of the cell wall

  found in plant, algal and fungal cells:

  - outside of cell membrane

  - plants: made from cellulose

  - algal cells: made from cellulose or glycoproteins

  - fungal cells: chitin
• what is the function of the cell wall

  - supports the whole structure of the cell/plant as a whole

  - withstands osmotic pressure created by entry of water into the cell

  - aids movement of water through plant
• what is the structure of the vacuole

  - large organelle, surrounded by the tonoplast; single membrane

  - fluid inside: cell sap (salts, sugars, amino acids, wastes and pigments)

  
• what is the function of the vacuole

  - storage site for sugars and amino acids, can act as a temporary food store

  - supports plant by making cells turgid

  - may contain natural pigments; colours petals to attract pollinators
• what is a prokaryotic cell

  contains no membrane bound nucleus or organelles (bacteria)
• what are the 8 components of a bacteria cell

  - cell wall

  -plasma membrane

  - slime capsule (some)

  - flagellum (some)

  - cytoplasm

  - plasmid DNA

  - circular DNA

  - 70S ribosome
• how are images of bacteria taken

  electron micrographs
• what is the cell wall in bacteria made from

  made of murein: a mixture 2 polymers (polypeptide & polysaccharide)
• what is the function of murein cell wall

  - keeps the cell shape

  - protect from lysis under turgor pressure

  - protects from physical damage

  - prevents entry of certain substances
• what is the purpose of the slime capsule

  - outside of cell wall, for protection against other cells

  - helps stick together for further protection
• what is the purpose of the cell-surface membrane

  - controls the entry and exit of substances between cell and external environment
• what is the function of circular DNA

  contains genetic information for the replication of new cells and coding for proteins
• what is the function of ribosomes in bacteria

  free ribosomes for protein synthesis: not attached to RER and smaller than eukaryotic (70S not 80S)
• how is food stored in bacteria

  food stored as glycogen or oil droplets
• where does genetic material exist in bacteria cells

  exists as circular DNA
• what are plasmids & their function

  - small circular fragments of DNA

  - can replicate themselves

  - contains genes that aid survival in adverse conditions (e.g enzymes that break down antibiotics)
• what is the purpose of the flagella

  one or more: for locomotion
• list 3 differences between prokaryotic and eukaryotic cells

  P = no membrane-bound organelles

  E = membrane-bound organelles (mitochondria)

  P = no nucleus, but an area where circular DNA is found

  E = nucleus has a nuclear envelope and DNA in linear chromosomes

  P = DNA may form plasmids

  E = no plasmids

  also:

  ribosome size, chloroplasts, cell wall material, capsule, association with proteins
• how do cells divide in prokaryotic cells

  by binary fission
• what is the process of binary fission

  - the circular DNA is copied once, plasmids many times

  - the 2 DNA loops attach to the membrane

  - membrane elongates between DNA molecules and pinches inward, forming 2 cells

  - a new cell wall forms, dividing original into 2 identical daughter cells
• are viruses alive

  no, they're non-living because they can't reproduce on their own