2.1.1 Cell Structure Flashcards

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1
Q

Cell Surface Membrane / Plasma Membrane

A

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.

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2
Q

Cellulose Cell Wall

A

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

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3
Q

Nucleus

A

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.

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4
Q

Lysosome

A

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.

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5
Q

Ribosome

A

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.

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6
Q

Rough Endoplasmic Reticulum (RER)

A

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.

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7
Q

Smooth Endoplasmic Reticulum (SER)

A

Function:
Synthesises proteins and lipids, as well as storage.

Description:
Network of membranes enclosing flattened sacs (cristae). Connected to the outer nuclear membrane.

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8
Q

Vesicle

A

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

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9
Q

Golgi Apparatus

A

Function:
Modifying proteins and packaging them into vesicles (secretory or lysosomes).

Description:
Structure of flattened, membrane-bound sacs (cristernae) with no ribosomes.

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10
Q

Mitochondrion

A

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.

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11
Q

Chloroplast

A

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.

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12
Q

Centriole

A

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.

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13
Q

Cilia

A

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.

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14
Q

Flagella

A

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.

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15
Q

Cytoskeleton

A

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

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16
Q

Nucleolus

A

Function:
Responsible for producing ribosomes necessary for protein synthesis.

Description:
Area within nucleus made up of proteins and RNA. RNA is used to produce ribosomal RNA (rRNA), which then combines with proteins to form ribosomes.

17
Q

Nuclear Envelope

A

Function:
Double membrane contains the DNA to protect it from damage/chemical reactions in the cytoplasm. Allows movement of molecules into and out of the nucleus through pores.

Description:
Envelope contains pores to allow smaller molecules to be exported to the rest of the cell cytoplasm, e.g. RNA. Consists of an outer membrane and an inner membrane.

18
Q

Making a Protein

A

1) Nucleus - site of ribosomes and mRNA manufacturing (copy of protein gene)
2) Ribosomes on the RER make secretory proteins (extracellular) and free ribosomes in the cytoplasm make intracellulaire proteins
3) Vesicles transport proteins from the RER to the Golgi apparatus
4) Golgi apparatus modifies the proteins (e.g. adding a glucose chain to make glycoproteins - used in cell signalling)
5) Vesicles containing proteins then pinched off of the Golgi apparatus and move towards the plasma membrane
6) Vesicles fuse with the plasma membrane and undergo exocytosis

19
Q

Light Microscope

A

Uses: uses light rays to observe objects

Advantages: 
can observe living specimens
does not use harsh chemicals
they are easy to set up
relatively cheap
portable
Disadvantages: 
low magnification (up to x2000)
low resolution (resolving power 200nm)
20
Q

Transmission Electron Microscope

A

Uses: view cell ultrastructure (organelles) in more detail

Advantages:
Over x500 000 magnification
Clear resolution (resolving power 0.5nm)

Disadvantages:
Expensive
Can only be used in carefully controlled environment
Take up space (not portable)
Complex to prepare specimens
Artefacts (marks, bubbles etc. on slide) can be difficult to remove

21
Q

Scanning Electron Microscope

A

Uses: view the appearance of different organisms on the surface of the cells

Advantages:
produces 3D images of surfaces
Over x500 000 magnification
High resolution (resolving power 3-10nm)

Disadvantages:
Expensive
Can only be used in carefully controlled environment
Take up space (not portable)
Complex to prepare specimens
Artefacts (marks, bubbles etc. on slide) can be difficult to remove

22
Q

Laser Scanning Confocal Microscope

A

Uses: uses a laser beam of light to illuminate chemical stains within the specimen (shows up fluorescent)

  • diagnosis of eye diseases
  • endoscopic procedures
  • development of new drugs
  • virtual biopsies
Advantages:
Better illumination 
Non-invasive
High resolution 
Can see distribution of molecules 

Disadvantages:
More expensive than light microscope
More complex than light microscope