mid sem exam Flashcards
Describe:
ribosomes
Complexes of 2 subunits with ribosomal RNA (rRNA) and protein.
in cytosol or in RER
describe:
smooth ER
smooth endoplasmic reticulum involves metabolism of carbohydrates and some protein synthesis.
.Describe:
golgi aparatus
folded membranes, unconnected
transporter, can modify proteins
.Describe:
Lysosomes
hydrolytic enzymes and lysosomal membrane produced in the rough ER
.Describe:
Vacuole
- Food vacuole
• Formed by phagocytosis
– Contractile vacuole
• Pump excess water out of cell to maintain
suitable ion concentration
– Central vacuole
• Contains cell sap, major role in plant growth
.Describe:
cell membrane
Phospholipids are amphipathic, held together through hydrophobic interactions.
developed in the ER and the Golgi contains proteins, carbohydrates and cholesterol.
Describe
cell membrane viscosity
Cholesterol decreases the fluidity allowing for cold.
The membranes Unsaturated fatty acids will have kinks in it causing it to be more liquidy or less viscous. However the Saturated fatty acids do not have kinks and will be more viscous.
.Describe:
use of proteins on cell membrane
Transport: provide a channel for passage of proteins
Enzymatic activity:
Signal transduction:
Cell to cell recognition: by recognising the carbohydrates
Intercellular joining:
Attachment of the cell membrane to the cells cytoskeleton:
Describe:
use of membrane carbohydrates
.used in cell recognition for proteins of other cells to recept
Describe:
Transport though the cell membrane
Active and passive.
Diffusion allows non-polar molecules pass through by even charge distribution though concentration gradient.
Transport channel proteins provide a pathway
Aquaporins allow water to transport
Carrier proteins, pump molecules through energy
Endocytosis, expends large energy
Describe:
cells in hypo/hypertonic solution
Animal cells lyse in hypotonic solution, shrivel in hypertonic solution. plant cells do neither because of cell wall, they become turbid.
Define:
lipopolysaccharides
Molecules consisting of a lipid and a polysaccharide composed of O-antigen. Found in the outer membrane of Gram-negative bacteria.
Define
microbiome
Means all of the microbes in a community
Human microbiome, refers to the collective genome of resident microorganisms in the human body
Define
pathogen and peptidoglycan
A bacteria or virus that may be able to spread disease.
Polymer of sugars and amino acids forming a cell wall.
Describe
what prokaryotes are composed of
Plasma membrane
Cytoplasm includes cytosol and structures within.
DNA
Ribosomes
Describe:
cell walls of prokayotes
.gram-positive, thick wall of peptidoglycan, resists molecules passing, becomes dark through iodine alcohol
Gram negative has less peptidoglycan with an outer membrane of lipopolysaccharides
Explain
how might prokaryotes be helpful to the biosphere
they recycle many important molecules. Such as fixing atmospheric nitrogen into ammonia.
Explain:
how antibiotic resistance can come about
Evolve resistance to drugs through genetic diversity. Can occur through mutation during binary fission
explain:
how prokaryotes may have genetic diversity
Transformation which has the uptake of DNA from surroundings
Transduction has phages carry genes from one cell to another
conjugate where a doner and a recipient pass DNA, a gene determines F+ or F- status a pilus transfers the F plasmid.
describe
viral replication
obligate intracellular parasites, inside cells, genetic material is released from the capsid, the DNA or RNA is replicated using the hosts replicating process, the replicated genes are combined with replicated coats and can lyse the cell, Lytic. Or they become part of the cell integrating their DNA, Lysogenic.
describe
virus structures
Complex (bacteriophage)
Spherical (influenza)
Rod shaped (tobacco)
describe
bacterial restriction enzymes
used to stop phage replication. Bacterial DNA is kept safe through DNA methylation
Describe
antigen, T cells and B cells
antigen is anything that can elicit an immune response that is foreign.
T cells: kill foreign cells (through contact or immune system cell aid)
B cells: make antibodies (bind to foreign molecule, triggering immune response)
describe
macrophage
macrophage, will engulf an antigen and digest it through the lysozyme, antigen are held on the outside of the plasma membrane of the macrophage which will be used to identify through the MHC complex.
Describe:
process of antigen with macrophage
Intracellular proteins degrade in proteasomes
Peptides of amino acids are present
Antigenic peptides made by proteasomes move to the ER
MHC molecules bind to antigenic peptides
Complex is moved through Golgi then to cell surface
Presented to T cells
Describe
plasmid
Extrachromosomal DNA which is self replicating.
Describe
Where DNA is found in eukaryotes
DNA found in the mitochondria and chloroplast usually single circular chromosomes, also in nucleus.
Describe
Structure of DNA
Hydrophilic sugar(deoxyribose)-phosphate back, hydrophobic bases, giving double helix.
phosphate connects to the sugar connected to the base
A=T has a double bond, while C-G has a triple bond.
5’ end is phosphate
3’ end is growing end and hydroxl
Describe
the two types of bases
purine(AG)
pyrimidine(CUT)
Describe
DNA polymerase
Only works in the 3’ to 5’ direction on template strand and is called DNA polymerase 3.
Produces strand in 5’ to 3’ direction
Describe
DNA replication
Topoisomerase breaks, swivels and rejoins parental DNA before the replication fork (unraveling, lessening stress). Helicase unwinds DNA strands. Each strand has single-strand binding proteins which stabilise the strands.Primase synthesises RNA primers as templates for DNA pol 3.
Describe
synthesised strands in replication bubble
Leading strand made towards replication fork. DNA pol 3 moves in 5’->3’ direction
Lagging strand, present are okazaki fragments. primase and DNA pol 3 enzymes required, ligase must join fragments.
Describe
use of DNA pol 1
RNA primer needs to be replaced because it isn’t stable, DNA polymerase 1 reads the DNA and removes the RNA primer.
Describe
Central dogma
expresses how DNA → RNA → Protein, and how this process is irreversible
describe
transcription
Initiation: RNA pol 2 binds to template strand at promotor.
Elongation: Reads, unwinds, produces
Termination: hits the Termination site with a specific combination
Describe
mRNA post transcription
5’end has a nucleotide cap and 3’ end has a poly-A-tail
Splicing also occurs in the pre-mRNA once made from the DNA. The Introns are spliced out with a spliceosome(small RNA molecules)
Describe
Translation
Initiation: mRNA, initial tRNA and 2 ribosome subunits come together
Elongation: codons recognised, peptide bond formed, costin GTP then Translocation
Termination: Stop codon reached, accepting release factor, promoting hydrolysis of bond between final tRNA in P site, subunits dissociate.
Describe
strands on DNA
3”->5” is the template strand while the 5’->3’ is the coding strand.
Template strand is read by RNA pol 2
Describe
polypeptide location targeting
Signal peptides are amino acid sequences in protein used to target protein to location, may be exercised during targeting
Define
Chromatin
Structure of DNA and histones that form chromosomes.
Define
Centromere and Chromsome
Centromere is a region of DNA on the chromosome, where sister chromatids overlap (each chromatid has a centromere). Chromosomes can be singular, or duplicated and made of 2 chromatids.
Describe
Cell cycle of mitosis
Interphase:
G1:
S: DNA replication, chromosomes duplicated (synthesis)
G2: chromosomes are duplicated but uncondensed.
Prophase: Chromosomes duplicated, formation of early mitotic spindle
Prometaphase: kinetochore formation, spindle slign at poles
Metaphase: formation of metaphase plate (chromosomes in a line)
Anaphase: separation of chromatids, (cytokinesis events occur at the end)
Telophase: nuclear envelope formation, cleavage furrow/formation of central cell wall
Describe
Sexual life cycle of animals
gametes (n) are fertilised, forming zygote (2n) which goes through mitosis forming diploid multicellular organism, meiosis occurs to form gametes once more.
This is different to plants and fungi.
Describe
1st stage of meiosis
Interphase:
Prophase 1: duplicated homologous chromosomes (2n) pair up and crossover, spindle microtubules form nuclear envelope breaks down. Synapsis occurs
Metaphase 1: chromosomes (4n) line up along equator, kinetochore microtubules form. [independent assortment of where they align]
Anaphase 1: homologous chromosomes separate, sis pairs remain.
Telophase 1 (cytokinesis) : haploid cells form (cleavage furrow), nucleus forms. Chromosomes (n2)
Describe
2nd stage of meiosis
Prophase 2: duplicated homologous chromosomes (2n) pair up and crossover, spindle microtubules form nuclear envelope breaks down. Metaphase 2: chromosomes (2n) line up along equator, kinetochore microtubules form. [independent assortment of where they align] Anaphase 2: Sis pairs separate. Telophase 2 (cytokinesis): haploid daughter cells / nucleus form, chromosomes (1n)
Describe
non-dis junction
Non-disjunction occurs when more or less chromosomes are pulled to one side during anaphase 1 or 2 of meiosis. Resulting in changes to the number of chromsomes in cells
Describe
binary fission
Replication begins at origin of replication on DNA
Cell elongation occurs during replication
Tubulin-like protein pinches inwards on plasma membrane
New cell wall formed
Identical cells formed.
Describe
chromosomes in humans
46 chromosomes in each somatic cell, or 23 homologous pairs. 22 autosomes and one pair of sec chromosomes. Homologous chromosomes are similar chromosomes from paternal genes.
Describe
Phospholipid
2 fatty acids which connect to a glycerol which connects to a phosphate head.
And like proteins and cholesterol and carbohydrates.
Describe
sites of ribosome
Codon read at the A site, the P site has the polypeptide being formed, and the E site is where the mRNA passes through and the tRNA is disassociated.
Describe and Explain
Reasons for sweat
to cool down through evaporation, from all sweat glands.
response to emotional stress, fatty sweat released from apocrine glands.
Describe
Reabsorbtion in sweat glands
Cold causes sodium reabsorbtion, resulting in water diffusion through osmosis thus less sweat.
Describe
antipersperant
antipersperant ions taken into cells of sweat ducts, water follows by osmosis
