2.1.1 Cell Structure Flashcards
Cell Surface Membrane / Plasma Membrane
Function:
Regulates the movement of substances into and out of the cell. Has receptor molecules allowing it to respond to chemicals like hormones.
Description:
Selectively permeable and made up of lipids and proteins, has receptor molecules.
Cellulose Cell Wall
Function:
Supports the individual cell and the plant as a whole and acts as a defence mechanism (against pathogens). Freely permeable so substances can move into and out of the plant cell.
Description:
made of cellulose (complex carbohydrate), rigid structure surrounding plant cells
Nucleus
Function:
Contains DNA molecules. Controls the metabolic activities of the cell by directing the synthesis of all proteins required by the cell. DNA binds with histone proteins to form a chromatin complex. Chromatin condenses to form chromosomes.
Description:
large organelle surrounded by a nuclear envelope (double membrane) containing nuclear pores.
Lysosome
Function:
Specified form of vesicles containing hydrolysis (digestive) enzymes. Break down waste material in the cells e.g. old organelles. In the immune system they break down pathogens ingested by phagocytic cells. Role in programmed cell death (apoptosis)
Description:
Round, single-membrane organelle/sac with fluid filled inside.
Ribosome
Function:
Free floating in the cytoplasm or attached to endoplasmic reticulum (to form RER). Site of protein synthesis.
Description:
Made of RNA molecules and proteins, not surrounded by a membrane.
Rough Endoplasmic Reticulum (RER)
Function:
Responsible for folding and processing proteins made at the ribosomes, as well as the transport.
Description:
network of membranes enclosing flattened sacs (cristae). Surface is covered with ribosomes.
Smooth Endoplasmic Reticulum (SER)
Function:
Synthesises proteins and lipids, as well as storage.
Description:
Network of membranes enclosing flattened sacs (cristae). Connected to the outer nuclear membrane.
Vesicle
Function:
For transport of substances in and out of cells (through the plasma membrane) and between organelles. Also for storage.
Description:
Small fluid-filled sac with a single membrane
Golgi Apparatus
Function:
Modifying proteins and packaging them into vesicles (secretory or lysosomes).
Description:
Structure of flattened, membrane-bound sacs (cristernae) with no ribosomes.
Mitochondrion
Function:
Site of final stages of cellular respiration (produces ATP). Large numbers in very active cells that require a lot of energy e.g. muscle cells. Also contain small amounts of mitochondrial DNA (mtDNA) so they can reproduce themselves.
Description:
Oval shaped and has a double membrane. The inner membrane is folded to form cristae (increases SA). Inside the cristae is the matrix, fluid interior which contains enzymes involved in respiration.
Chloroplast
Function:
Function:
Site of photosynthesis - light dependent happens in the grana, which contains chlorophyll pigments, other parts happen in the stroma. They contain DNA and ribosomes to make their own proteins.
Description:
Small, flattened structure found in plant cells. Has a double membrane as well as membranes inside called thylakoid membranes, which are stacked up to form grana (increase SA). Grana are linked together by lamella (thin flat thylakoid membrane pieces). The fluid enclosed inside is called the stroma.
Centriole
Function:
Two associated centrioles form a centrosome, which produce spindle fibres involved in the separation of chromosomes during cell division (mitosis and meiosis).
Description: hollow cylinders made of microtubules found in animal cells and some plant cells.
Cilia
Function:
Can be mobile or stationary-
Stationary present on surfaces of cells, important in sensory organs e.g. nose.
Mobile- beat rhythmically creating a current, used to move substances along the cell surface e.g. in trachea to move mucus away from the lungs
Description:
Small hair-like structures on the plasma membrane of some animal cells. Each clilium contains 2 central microtubules surrounded by a wheel of 9 pairs of microtubules (9+2 arrangement). When pairs of parallel microtubules slide over it causes a beating motion.
Flagella
Function:
Enable cells motility- propels cells forward e.g. sperm cell. Sometimes used as a sensory organelle to detect chemical changes in the cell’s environment.
Description:
Protrude from cell surface surrounded by plasma membrane, longer than cilia. Similar structure of the 9+2 microtubule arrangement.
Cytoskeleton
Function:
Provides mechanical strength within cells, necessary for shape and stability of a cell. It also enables cell movement and movement of organelles within a cell.
Description:
Microfilaments- contractile fibres formed from actin protein. They are responsible for cell movement and contraction during cytokinesis
Microtubules- globular tubulin proteins polymerised to form tubes. They determine the shape of a cell and act as a track to enable movement of vesicles around the cell
Intermediate fibres- give mechanical strength to cells, help maintain structure
