❌❌[unused] 1.2 Cells as the basic units of living organisms Flashcards
(37 cards)
cell theory
-all living things made up of cells
-cells: smallest working units capable of performing life functions in all living things
-all cells come from pre-existing cells through cell division
animal cell
-plasma membrane enclosing membrane-bound nucleus & organelles
-small vacuoles
-no chloroplasts
-no cell wall
plant cell
-no centrioles, no lysosomes, no cilia, no flagella (except some photosynthetic protists)
-yes: rigid cell wall, central vacuole, chloroplasts
bacteria
no nucleus
& no organelles EXCEPT ribosomes
prokaryotes (bacteria)
- no membrane-bound structures
- no nucleus
-unicellular - d= ~1-5um
- 70S ribosomes
- circular DNA
- peptidoglycan cell walls
virus
-not living, not consisting of cells, not-living replicating cells
-yes genetic material (RNA/DNA)
-similar to other living ogranisms
-naryotes
-2 ways:
- host bursts; LYTIC CYCLE
- infect host cell
co-opt cellular machinery, (DNA replication/protein synthesis)
⭐ produce more viral proteins
host bursts
⭐ viral particles spread
- host lives & divides;
LYSOGENIC CYCLE
infect host cell
co-opt cellular machinery dna rep/protein syn.
host lives; host divides
viral STRUCTURAL FEATURES (2)
- nucleic acid core DNA or RNA (code viral proteins to replicate)
- capsid protective coat of proteins
[some viruses have outer envelope made of phospholipids]
prokaryotes vs eukaryotes
size, organelles, genetic material, cell wall, ribosomes
pro: D=
⭐ ~1-5um,
no membrane-bound structures, no nucleus, no ER,
circular DNA in cytoplasm, peptidoglycan cell wall, 70S ribosomes
eu:
D=10-100um,
many membrane-bound organelles, yes nucleus, yes ER,
linear DNA in chromosome in nucleus,
plants cellulose cell wall, animals no cell wall,
cytoplasm 80S ribosomes, mitochondria/chloroplasts 70S
cell membrane
- surround cytoplasm of all cells (plants=between cell wall & cytoplasm)
-very thin
-phospholipid bilayer
-regulate nutrient and waste transport in and out of cell
cytoplasm
-within cell membrane
-dependent on cell size/number/vacuole size
-jelly-like matrix on dissolved nutrients & salts
-contains organelles, sugars, amino acids & proteins for growth & reproduction
-aid material movement, cell shape & organelle network
nucleus
-central area within cytoplasm
-seen with light microscope (10% of cell volume, ~1um)
⭐ double-layered membrane with pores
⭐ contains chromosomes DNA and nucleoli
nuclear envelope
-surround nucleus, thin layer
- lipid layers (like cell membrane)
- forms part of ER
- nuclear pores = regulate passage btwn nucleus & cytoplasm,
RNA travel thru to reach ribosome (transcription => to translation)
nucleolus
-inside nucleus
-produce ribosome; ribosome synthesis
=> rRNA genes
- make ribosomal subunits
-units exit nucleus
-combine with proteins in cytoplasm
-form functional ribosomes
-made of proteins, RNA, DNA
ER
endoplasmic reticulum
- around nucleus with shared membranes
-smooth & rough
- large organelle with continuous membrane network of flattened sacs and branching tubules
rough ER
-production and processing proteins to be exported/secreted
-ribosomes attached (proteins)
smooth ER
-lipid fat production
-carbohydrate metabolism
-drug/poison detoxification
-store calcium & its metabolism
Golgi Apparatus/Body (CDC: cell delivery center)
- NEAR NUCLEUS in cytoplasm
-large
-single membrane lined sac filled with liquid and nutrients
-distribution & transportation of cell’s chemical products through vesicles
-modifies proteins and lipids
MITOCHONDRIA
-spread within cytoplasm
-numbers DEPENDENT on tissue & energy needs.
-double membrane with embedded PROTEINS.
-centre filled with nutrient-rich MATRIX LIQUID.
-has small circular DNA coding functional proteins.
-cellular respiration (glucose => ATP, Adenosine triphosphate)
ribosome (‘factory’)
- most are BOUND to ER, endoplasmic reticulum, some free-floating in cytoplasm, found within other organelles
-80S vs 70S (S = svedberg unit = measure how fast substance sediment in centrifuge)
-protein synthesis
(translate RNA to proteins)
lysosome
-single layer membrane
DIGESTIVE (hydrolytic) enzymes
-exocytosis [the process by which cells excrete waste and other large molecules from the cytoplasm to the cell exterior]
/endocytosis (taking in of matter by a living cell by invagination of its membrane to form a vacuole.)
-autophagy (self-consume)
-rid waste products
centrioles
9 groups of 3 microtubules each; for each centriole
- EUKARYOTIC ONLY
perpendicular pair near nucleus
-microtubules (tubulin protein, hollow)
microtubules
- CYTOSKELETON
- tubulin protein (alpha&beta) => dimer => protofilament
