1 — cells Flashcards
Characteristics of cell membrane
- Partially permeable
- Controls movement of substances entering/leaving the cell
- 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
- May contain >/1 nucleoli & chromatin, which contains genetic information, DNA
- 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 [1] for cellular activities [1] (such as) Growth and 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
Similarities betw a typical plant cell n an animal cell
Both has presence of protoplasm and presence of RER+SER
Movement of proteins in cells
- Proteins made / synthesised by the ribosomes on the rough endoplasmic reticulum (RER) enter into RER. [1]
- The manufactured proteins are transported in vesicles that are pinched off from the RER and are transported to the Golgi apparatus. [1]
- The Golgi apparatus stores and chemically modifies the proteins made by RER and packages them into vesicles. [1]
- The secretory vesicles containing the modified proteins are pinched off from the Golgi apparatus. The vesicles then move to the cell membrane and fuse with the membrane. This releases the contents in the vesicles into the outside of the cell. [1]