Introduction to the cell Flashcards
Prokaryote cell vs eukaryote cell
Both have:
The plasma membrane, cytosol, DNA, RNA, protein ribosomes
Cytoplasm
The cytoplasm is everything inside the plasma membrane including the organelles, but not including the nucleus
cytosol
The fluid portion of the cytoplasm is the cytosol
cytosol胞液，细胞溶质
water
dissolved substances
suspended悬浮的 substances
Cytoplasm 细胞质
Major organelles include:
Nucleus Endoplasmic Reticulum (smooth and rough) Golgi apparatus Lysosomes Mitochondria Ribosomes
Plasma membrane质膜
double layer of phospholipids with embedded proteins
hydrophilic亲水 polar heads (phosphate)
hydrophobic疏水 lipid tails (fatty acids)
arranged as a double layer around cytoplasm, tail to tail
Plasma Membrane proteins
Integral proteins 整合蛋白:
embedded(partially or fully) into the membrane
eg. Transmembrane proteins跨膜蛋白: integral membrane proteins that fully span the entire membrane, contact extracellular细胞外的 and cytoplasmic细胞质的 areas
Peripheral membrane proteins外周膜蛋白: associated with the membrane, but not actually embedded in it
What do the plasma membrane proteins do?
- Transport:
For example, channels, transporters, may be general or selective, gated or not - Enzymatic activity:
Carry out a chemical reaction, may or may not be a part of a team of enzymes - Signal transduction:
External signalling molecule causing transduction of information to the inside of the cell
More jobs for plasma membrane proteins
- cell-cell recognition:
Use of glycoproteins (carbohydrate + protein) as molecular signatures of the extracellular side of the cell
- intercellular joining:
For example, gap junctions or tight junctions.
6.attachment to the cytoskeleton and extracellular matrix:
For example, fibronectin mediates contact between cell surface integrins and ECM (eg. collagen).can facilitate movement
Nucleus
Functions:
- to house/protect DNA in eukaryotic cells
- make RNA and assemble ribosomes
- pores regulate the movement of substances (eg. protein and mRNA) in and out
- molecule segregation to allow temporal and spatial control of cell function
In the nucleus: Deoxyribonucleic Acid (DNA)
DNA wrapped 2x around a group of 8 histones, to form nucleosomes collectively known as chromatin
In the nucleus: Deoxyribonucleic Acid (DNA)
As the cell prepares for cell division, chromatin condenses further to chromatin fibre then condenses further into loops then stacks as chromosomes.
Ribosomes核糖体
Function: protein production (translation), found in two places within the cell:
free in the cytoplasm - making proteins to be used in the cytosol (non-endomembrane内膜 destinations)
attached to the RER - making non-cytosolic细胞溶质的 proteins/endomembrane
Endoplasmic Reticulum内质网
The ER is an extensive广泛的 network of tubes and tubules, stretching out from the nuclear membrane
Rough Endoplasmic Reticulum
The major function is the production of:
•Secreted proteins
•Membrane proteins
•Organelle proteins
Rough Endoplasmic Reticulum
粗面内质网
continuous with nuclear envelope dotted with attached ribosomes
Rough Endoplasmic Reticulum
The major function is the production of:
•Secreted proteins分泌性蛋白
•Membrane proteins膜蛋白
•Organelle proteins细胞器的蛋白质
Rough Endoplasmic Reticulum
Rough ER membrane surrounds the protein to form transport vesicles运输小泡 destined for the Golgi
Smooth Endoplasmic Reticulum
Lacks ribosomes: doesn’t make proteins
Smooth Endoplasmic Reticulum
The major function is as a housing unit for proteins and enzymes
Smooth Endoplasmic Reticulum
Synthesizes lipids, including steroids and phospholipids
Smooth Endoplasmic Reticulum
Storage of cell-specific proteins, not all cells make all proteins
Examples:
Liver: houses enzymes for detoxification解毒 and for glucose release
Muscle: calcium ions (refer ET: M)
Golgi apparatus高尔基体,内网器 –receiving and modifying改造
This complex is made up of 3-20 flattened membranous扁平膜囊 sacs called cisternae池, stacked on top of one another (“pita bread”)
Golgi apparatus –receiving and modifying
Functions: modify, sort, package and transport proteins received from the rough ER using enzymes in each cisternae.
Golgi apparatus –receiving and modifying
Formation of:
•secretory vesicles分泌小泡 (proteins for exocytosis胞外分泌)
•membrane vesicles膜囊泡 (PM molecules)
•transport vesicles运输小泡 (molecules to lysosome溶酶体)
Golgi apparatus: to destination
Each sac or cisternae contains enzymes of different functions
proteins move cis to trans from sac to sac
mature at the exit cisternae
travel to destination
Modifications修改 occur within each sac
(formation of glycoproteins糖蛋白, glycolipids糖脂 and lipoproteins脂蛋白)
Lysosomes 溶酶体
vesicles囊泡；小水泡 formed from Golgi membrane
membrane proteins pump H+in to maintain acidic pH
rest of cell protected by membranes
Lysosomes
The main function is digestion of:
- substances that enter a cell
- cell components e.g. organelles -autophagy自噬
- entire cells -autolysis自身溶解
Mitochondria
Main function: generation of ATP through cellular respiration
Mitochondria are made up of:
- Outer mitochondrial membrane
- inner mitochondrial membrane, with folds called cristae
- Fluid filled interior cavity, called the mitochondrial matrix线粒体基质
Mitochondria
The mitochondria are not part of the endomembrane system.
Mitochondria – the ATP factory
The transfer of phosphate to another molecule provides energy
Cytoskeleton 细胞骨架
Fibres or filaments丝 that help to maintain the size, shape and integrity完整性 of the cell:
- Act as scaffolding脚手架 across the cell
- Involved in intracellular细胞内的 transportation and cell movement
Cytoskeleton
Three types of fibres (from smallest to largest):
Microfilaments微丝
Intermediate filaments中间丝
Microtubules 微管
Cytoskeleton: microfilaments
Diameter: 7 nm
Comprised of actin肌动蛋白 molecules assembled in two long chains, twisted around each other
Found around the periphery外围 and lining the interior of the cell
Cytoskeleton
Three types of fibres (from smallest to largest):
Microfilaments微丝
Intermediate filaments中间丝
Microtubules 微管
Cytoskeleton: intermediate filaments中间丝
Diameter: 8-12 nm.
Comprised of a diverse range of different materials; one example: keratin角蛋白
Found in the cytoplasm of the cell.
Cytoskeleton: intermediate filaments
Function:
- bear tension and weight throughout the cell, e.g., during cell anchoring锚定,
- act as a scaffold脚手架 for cellular organelles, e.g., the nucleus.
Usually the most permanent永久 of the cytoskeleton
Cytoskeleton: microtubules 微管
Diameter:
tubular structure, 25 nm with the central lumen of 15 nm diameter. Comprised of tubulin dimers (alpha and beta), coiled, to form a tube Extends from centriole into cytoplasm/nucleus
Cytoskeleton: microtubules
Functions:
- Support cell shape and size
- Guide for movement of organelles, •e.g., vesicles from Golgi to membrane
- Chromosome organization – cell division
- Support and movement of cilia/flagella
Assembled and disassembled as required -are dynamic
Cytoskeleton: microtubules 微管
Diameter:
tubular管状 structure, 25 nm with the central lumen内腔 of 15 nm diameter. Comprised of tubulin微管蛋白 dimers二聚物 (alpha and beta), coiled, to form a tube Extends from centriole细胞中心粒 into cytoplasm/nucleus
Cytoskeleton: microtubules
Functions:
- Support cell shape and size
- Guide for movement of organelles, •e.g., vesicles囊泡；小水泡 from Golgi to membrane
- Chromosome organization – cell division
- Support and movement of cilia/flagella
Assembled and disassembled as required -are dynamic
