Unit 2 - cells Flashcards
(23 cards)
outline the role of organelles in the production, transport and release of proteins from eukaryotic cells
-DNA in the nucleus codes for proteins
-mitochondria produce ATP for protein synthesis
-ribosomes synthesise proteins
-golgi apparatus package
-vesicles transport
-vesicles fuse with cell surface membrane (exocytosis at cell membrane)
describe the structure and function of the endoplasmic reticulum
RER: folded membrane called cisternae with ribosomes attached, protein synthesis
SER: folded membrane called cisternae, lipid synthesis and stores lipids and carbohydrates
Describe the structure and function of the golgi apparatus and vesicles
-structure: folded membrane cisternae, secretary vesicles pinch off from the cisternae
-function: form lysosomes, form glycoproteins, transport modify and package lipids, products are transported to the cell surface in golgi vesicles where they fuse with the membrane releasing the products.
Describe the function and structure of lysosomes
-structure: bags (vesicles) of digestive enzymes
-function: hydrolyse phagocytic cells, break down dead cells (autolysis), exocytosis - release enzymes to outside of the cell to destroy material
describe the structure and function of the mitochondria
-structure: double membrane, inner membrane called cristae, fluid centre called mitochondrial matrix, loop of mitochondrial DNA
-function:site of aerobic respiration, site of ATP production, contains DNA to code for for enzymes needed in respiration
describe the structure and function of ribosomes
-structure: made of two sub units of protein and rRNA, 80s found in eukaryotic cells, 70s found in mitochondria and chloroplasts
-function: site of protein synthesis
describe the structure and function of the vacuole
-structure: filled with fluid surrounded by a single membrane called the tonoplast
-function: makes cell turgid, provides cellular support, temporary store of sugars and amino acids
describe the structure and function of chloroplasts (plants)
-structure: surrounded by a double membrane, contains thylakoids (folded membrane imbedded with pigment), stroma
-function: site of photosynthesis
describe the structure and function of the cell wall (plants and fungi)
-structure: plants - made of microfibrils of cellulose, fungi - made of chitin
-function: provides structural support to the cell
describe the structure and function of the plasma membrane
-structure: phospholipid bilayer
-function: controls the movement of molecules in and out of the cell
describe how a phagocyte destroys a pathogen present in the blood
-engulfs the pathogen
-forms a phagosome and fuses with a lysosome
-lysosome releases lysozymes which hydrolyse the pathogen
describe the cell mediated response
-once a phagocyte has destroyed a pathogen, it will present the pathogens antigens on its surface
-helper T cells have receptors which will attach to the antigens
-this activates the helper T cells to divide by mitosis to replicate
-some remain as helper T cells and activate B lymphocytes
-some cloned helper T cells differentiate - some become memory cells for that antigen, some stimulate macrophages to perform phagocytosis, some become cytotoxic T cells
describe the role of cytotoxic T cells (killer T cells)
-they destroy abnormal or infected cells
-they release a protein (perforin) which embeds into the cell surface membrane, making a hole so that any substances can enter or leave the cell, this causes cell death
describe how HIV is replicated
-attachment proteins attach to receptors on helper T cell
-the HIV protein capsid fuses with the cells membrane, RNA and enzyme reverse transcriptase enters the helper T cell
-reverse transcriptase coverts RNA to DNA
-viral protein produced
-virus particles assembled and released from the cell
what is a monoclonal antibody
-a single type of antibody with the same 3D structure artificially produced from a single clone of plasma cells
how does HIV cause symptoms of AIDS
-the helper T cell count drop
-the immune system deteriorates and eventually fails
-the person is more vulnerable to other infections
-antibiotics do not work - as viruses use human metabolism and enzymes
Compare ways that DNA in chloroplast are different from DNA in the nucleus
-DNA in the chloroplasts is shorter than nuclear DNA
-DNA in the chloroplasts is circular whilst nuclear DNA is linear
-DNA in the chloroplasts is not associated with histones/proteins whilst nuclear DNA is
-DNA in the chloroplasts does not contain introns whilst nuclear DNA does
Compare eukaryotes to prokaryotes
-DNA in a eukaryote is enclosed in a nucleus whilst DNA in a prokaryote is free in the cytoplasm
-DNA in a eukaryote is long and linear whilst DNA in a prokaryote is circular
-DNA in a eukaryote is attached to histones whilst DNA in prokaryotes isnt associated with histones
-eukaryotes have membrane bound organelles but prokaryotes have no membrane bound organelles
Name and describe five ways substances can move across the cell surface into a cell
-simple diffusion of small, non-polar molecules down a concentration gradient
-facilitated diffusion of large, charged molecules down a concentration gradient using a a protein channel or carrier
-osmosis of water down a water potential gradient
-active transport against a concentration gradient via protein carrier using ATP
-co-transport of 2 substances using a carrier protein
What is active immunity and pros and cons
-when the immune system makes it’s own antibodies
-pro - long term as memory cells are produced
-cons - requires exposure to the antigen, response isn’t immediate
What is passive immunity and pros and cons
-antibodies are given from somewhere else eg children being breastfed by their mothers
-pros - doesn’t require exposure to the antigen, immediate protection
-cons -short term as memory cells not produced
Describe the structure of HIV
-RNA - contains the genetic material and some proteins like the enzyme reverse transcriptase
-capsid - an outer protein coating
-envelope - made of membrane from previous host cell
-attachment proteins - stick out from the envelope and attach to host helper t-cells
Compare the DNA in eukaryotes to the DNA in prokaryotes
-DNA in eukaryotes and prokaryotes are both made of DNA nucleotides containing a deoxyribose, a phosphate group and a nitrogenous base
-nucleotides in DNA in eukaryotes and prokaryotes are both joined by phosphodiester bonds to make a polymer chain
-eukaryotic DNA is linear whilst prokaryotic DNA is circular
-eukaryotic DNA is longer than prokaryotic DNA
-eukaryotic DNA is associated with histones whilst prokaryotic DNA is not
