1 — cells Flashcards
How single cells eventually form a system
Similar Cells -> different tissues working tgt to carry out a specific function -> organ -> system
E.g. muscle cells -> muscular tissues work with nervous & gland tissues to digest food -> forms organ: stomach
Light vs electron micrograph
- Light micrograph: coloured images
- Electron micrograph: black-and-white images, can be artificially coloured
Higher range of magnification
Characteristics of cell membrane
- Partially permeable
- Controls movement of substances entering/leaving the cell
- Filters by size
- Made up of lipids&proteins
Characteristics of Cytoplasm
- Site for chemical activities in cell to occur
- Contains specialised structures that perform a specific job within the cell: organelles
- Endoplasmic reticulum
- Golgi body
- Ribosomes
- Mitochondria
Characteristics of nucleus
- Surrounded by nuclear membrane
- Separates nucleus contents from the rest of cytoplasm
- May contain >/1 nucleoli & chromatin, which contains DNA
- Part of cytoplasm & protoplasm
- Controls cell activities, essential for cell division
Characteristics of cell wall
- Made of cellulose
- Protects cell from injury
- Gives the cell a fixed shape
- Fully permeable
Characteristics of chromatin
- Made up of proteins and DNA (deoxyribonucleic acid)
- stores hereditary info
- Carries instructions that a cell needs for carrying out its activities
- condense and shortens to become chromosomes
- Only present during mitosis (cell division)
Endoplasmic reticulum (smooth vs rough comparison)
Appearance:
RER: Appears rough cus of ribosomes attached to membrane
SER: Appears smooth cus absence of ribosomes attached to membrane
Shape:
RER: A network of flattened spaces lined with a membrane (filled with fluid)
SER: More tubular than RER
Connections:
RER: Continuous with nucleus membrane
SER: Continuous with RER
Functions:
RER: Transport proteins made by ribosomes to Golgi Apparatus for excretion out of cell
SER: - Synthesise fats & steroids (sex hormones in mammals)
- Carries out detoxification: Converts harmful substances -> harmless substances
Ribosomes
Sites to synthesise proteins
- Attached to RER membrane
- Proteins made transported out of cell (usually)
- Lie freely in cytoplasm
- Proteins made used within cell
Golgi Body/Apparatus (GB/A)
- Consists of stack of flattened spaces surrounded by membranes
- Chemically modifies, stores & packages substances made by ER in vesicles for secretion out of cell
Vesicles
- Transport substances within cell
- Contains substances made by ER, pinched off from ER -> fuse with GB, release contents into GB to be modified-> secretory vesicles (becomes secretory now) containing modified substances pinched off from GB -> move to cell membrane -> fuse with cell membrane -> contents released out of cell
Mitochondria
- Singular: mitochondrion
- Site for aerobic respiration where glucose is oxidised to release energy for cellular activities (such as)
- Growth
- Reproduction
- Glucose + oxygen -> CO2 + H2O + large amt of energy
Chloroplasts
Contains a green pigment chlorophyll required for photosynthesis to occur
Vacuoles
- A fluid-filled space enclosed by a partially permeable membrane
- Store substances within a cell
- Plant: large & central; contains cell sap
- Contains dissolved substances like sugars
- Mineral salts
- & amino acids
- Animal: many & small; contain water & food substances; usually exists temporarily
Differences betw plant cell n animal cells
Presence of cell wall:
PC: P (present)
AC: A (absent)
Vacuoles:
PC: Large, central, contains cell sap
AC: Many, small, contains water & food substances
Presence of chloroplasts
PC: P
AC: A
Presence of centrioles:
PC: A
AC: P