exam questions Flashcards
structure and functions of microtubules
structure:
hollow tubes made out of tubulin proteins
(9+2 formation in cilia and flagella)
function:
forms spindle fibres to pull apart sister chromatids in anaphase
forms track for motor proteins to transport vesicles
forms cilia (to waft mucus)
forms flagella (for sperm/bacteria movement)
all membrane bound organelles
nucleus
mitochondria
RER and SER
golgi apparatus and vesicles
lysosomes and peroxisomes
vacuoles
chloroplast
non membrane bound organelles
ribosomes
centrioles
cytoskeleton
nucleolus
what is the structure of a prokaryote
(from out to in)
- flagella (made of microtubules) for movement
- pili (hair-like structures) attaches prokaryotes together
- slime capsule protects immune system
- peptidoglycan cell wall to shape cell
- plasma membrane controls what enters and exits cell
- cytoplasm (gel like substance) site of metabolic reactions
- circular DNA (free floating) controls cell activity
- plasmid DNA can give antibiotic resistance that can be shared between bacteria
- 70s ribosomes site of protein synthesis
transverse
vs
longitudonal
transverse = horizontal across structure
longitudonal = vertical along structure
osmosis
net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane
Water potential (Ψ)
how concentrated a solution is
(pure water has the highest water potential of 0)
(adding solute to a solution makes it more -)
hypotonic solution meaning
the solution has a higher water potential (more pure) than the cell
plant vs animal cell in a hypotonic solution
water moves in to cell (down Ψ gradient)
plant becomes turgid (as cell wall strong)
animal cell bursts (lysis)
hypertonic solution
solution has a lower water potential than the cell
plant vs animal cell in a hypertonic (low water potential solution)
water moves out of cell into the solution
plants becomes plasmolysed#
animal cell shrinks
endosymbiotic theory
mitochondria and chloroplast where once prokaryotes that got engulfed by eukaryotes
what evidence backs the endosymbiotic theory
mito and chloro has:
- double membrane
- has its own circular DNA
- has 70s ribosomes
- they replicate independently
active transport
movement of molecules or ions against a concentration gradient using ATP and carrier proteins
prokaryotes vs eukaryotes
-prokaryote has no nucleus
-prokaryotes lack membrane bound organelles (mitochondria)
- prokaryotes have 70s ribosomes
- eukaryotes have 70s ribosomes
- prokaryotes reproduce via binary fission
- eukaryotes reproduce by meiosis
DNA vs RNA
- DNA is double stranded
- RNA is single stranded
- DNA has deoxyribose (lack an O)
- RNA has ribose
- DNA has thymine base
- RNA has uracil base
- DNA store genetic info
- RNA transfers genetic info
mitosis vs meiosis
- mitosis is for growth and repair of tissues
- meiosis is for formation of gametes
- mitosis has one division
- meiosis has two division
- mitosis produces 2 diploid cells
- meiosis produces 4 haploid cells
- mitosis forms identical cells
- meiosis forms non-identical cells
meiosis 1 and 2 steps
meioisis 1:
prophase 1: chromosomes condense and become visible, homologous chromosomes pair up, crossing over happens
metaphase 1: pairs line up at center
anaphase 1: spindle fibres pull homologous pairs apart to poles, sister chromatids remain together
telophase 1: cell membrane reforms splitting cell into two haploid cells
meiosis 2:
prophase 2: chromosomes condense and visible
metaphase 2: chromosomes align at the center
anaphase 2: sister chromatids separated by spindle fibres
telophase 2: cell membrane reforms splitting cells
final product= four non-identical haploid gametes
nucleotides structure
- phosphate group (circle)
- pentose sugar
- nitrogenous base (rectangle)
phosphorylated nucleotides
nucleotide that contains more than one phosphate group (e.g ADP and ATP)
drawing improvements
- use sharp pencil
- use clean single lines (no overlapping)
- no colouring or shading anything
- use horizontal lines for labels (no arrows)
- state magnifications
- add a title
transcription 6 marker
in nucleus
DNA gyrase unwind double helix
DNA polymerase unzips H bonds between complimentary nitrogenous bases
exposing template strand
polymerase moves along template strand
using complimentary base pairing to form a complimentary mRNA strand
RNA nucleotides form phosphodiester bonds
mRNA exits nucleus via nuclear pores
translation 6 marker
occurs at ribosomes (RER) and cytoplasm
mRNA strand binds to ribosomes
mRNA sequence read in codons
tRNA carrying specific amino acids binds to mRNA anticodon (complimentary to codon)
ribosomes catalyses peptide bonds forming between adjacent amino acids
the makes a polypeptide chain
this carries on till the stop codon reached, so polypeptide is released
what happens after translation
- RER folds proteins into secondary/tertiary structures
- protein is packaged into transport vesicle and transported to golgi apparatus via motor proteins and cytoskeleton
- proteins modified at golgi apparatus
(adds carbohydrate to form glycoprotein) - protein packaged into secretory vesicle
- moves out of cell via motor proteins along cytoskeleton
- vesicle fuses w plasma membrane to secrete protein by exocytosis
