1.2 cell structure and organisation Flashcards by Deleted Deleted

Define eukaryotic cell

A type of cell that contains a true nucleus
along with membrane-bound organelles.

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Describe the structure of the nucleus.

● Surrounded by nuclear envelope which is
semi-permeable and double membraned
● Nuclear pores allow substances to enter/exit
● Dense nucleolus (made of RNA and proteins) assembles ribosomes

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Describe the function of the nucleus.

● Contains DNA coiled around chromatin into
chromosomes
● Coordinates cellular activities

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What is chromatin?

A DNA-protein complex found in
eukaryotic cells.

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Describe the structure of mitochondria.

● Surrounded by double membrane, mitochondrial envelope
● Folded inner membrane forms cristae (large surface area)
● Fluid matrix contains mitochondrial DNA, respiratory enzymes, lipids and proteins

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Describe the function of mitochondria

Site of aerobic respiration to produce ATP

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Describe the structure of the endoplasmic reticulum (ER).

● Series of flattened membrane-bound sacs
(cisternae) within the cytoplasm, continuous with the nuclear envelope
● Two types: rough ER and smooth ER

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Describe the function of the smooth
endoplasmic reticulum (SER).

lipid synthesis

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Describe the function of the rough endoplasmic reticulum (RER)

Many ribosomes attached for protein
synthesis and transport

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Describe the structure of ribosomes.

● Made from rRNA and proteins
● Found free in the cytoplasm or
associated with the RER

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Describe the function of ribosomes

Site of protein synthesis (translation)
● Large subunit joins amino acids
● Small subunit reads RNA

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Describe the structure of the Golgi body.

● Planar stack of membrane-bound, flattened sacs
● Cis face aligns with RER
● Molecules are processed in cisternae
● Vesicles leave via trans face by exocytosis

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Describe the function of the Golgi apparatus

● Modifies and packages proteins for export
● Synthesises glycoproteins

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Describe the structure and function of
lysosomes

● Fluid-filled vesicles surrounded by a single
membrane, contain enzymes
● Role in phagocytosis,
contains digestive enzymes that break down macromolecules

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Describe the structure of centrioles.

● Cylindrical structure
● Organised into microtubules in a 9+0 pattern
● Found in pairs in centrosomes

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Describe the function of centrioles

● Migrate to opposite poles of the cell during
prophase
● Involved in the organisation of spindle fibres

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Describe the structure of a chloroplast.

● Disk shaped surrounded by double membrane
● Thylakoids - flattened discs stacked to form grana
● Grana - contain photosystems with chlorophyll
● Intergranal lamellae - tubes attach thylakoids in adjacent grana
● Stroma - fluid-filled matrix

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What is the function of a chloroplast?

site of photosynthesis

Describe the structure of the permanent vacuole in plants.

● Surrounded by a single membrane, tonoplast
● Contains cell sap (mineral ions, water,
enzymes, soluble pigments)

Describe the structure of the permanent vacuole in plants.

● Controls turgor pressure
● Water storage
● Isolates harmful waste products
● Maintains pH

Define plasmodesmata

Microscopic channels between plant cell
walls that facilitate communication and
symplastic transport.

Define prokaryotic cell

A type of cell that does not contain any
membrane-bound organelles or a true
nucleus

Describe the structure and function of the flagella in prokaryotic cells

● Long, whip-like protrusion made of flagellin
● Rotates to propel the organism
● Sensory organ

How is genetic information stored in prokaryotes?

● Plasmids - small rings of DNA that carry
non-essential genes, exchanged between bacterial cells via conjugation
● Loop of DNA - circular DNA stored in the nucleoid region of the cell

How is genetic information stored in prokaryotes?

● Plasmids - small rings of DNA that carry non-essential genes, exchanged between bacterial cells via conjugation ● Loop of DNA - circular DNA stored in the nucleoid region of the cell

Describe the structure and function of pili in prokaryotic cells

● Hair-like microfibers made of pilin that extend through the cell wall ● Enable the attachment of bacteria to each other and to other surfaces

Describe the structure and function of the mesosome

● Infolds of the cell membrane ● Increase the surface area of the cell, aiding cellular respiration

What is the function of the capsule in prokaryotic cells?

protective slimy layer Helps the cell to retain moisture and adhere to other surfaces

Which organelles are found in both eukaryotic and prokaryotic cells?

● Cell membrane ● Cytoplasm with a form of cytoskeleton (although cytoskeleton of eukaryotes is more significant) ● Ribosomes

Contrast eukaryotic and prokaryotic cells

Eukaryotic Large, often multicellular Contain membrane-bound organelles and true nucleus Linear chromosomes associated with histones 80S ribosomes Reproduce via sexual or asexual reproduction Cell wall made of cellulose (plants) or chitin (fungi) Extra DNA in some organelles, e.g. mitochondria

prokaryotic cells

Prokaryotic Small, unicellular No membrane-bound organelles, no nucleus Circular DNA, not associated with proteins 70S ribosomes Reproduce via binary fission Peptidoglycan cell wall Extrachromosomal DNA in plasmids

What is a light microscope?

A type of microscope that uses a series of lenses to magnify the visible light reflecting off a specimen.

What is magnification

The number of times bigger an image appears compared to the size of the specimen.

Describe cell theory

● The cell is the fundamental unit of all life forms ● New cells can be formed from existing cells ● Cells contain genetic material which can be transferred to daughter cells

What is a virus?

A non-living microorganism that consists of genetic material surrounded by a protein husk.

How do viruses differ from prokaryotic and eukaryotic cells?

Non-living Living Smaller and simpler in structure Larger and more complex structure Genetic material in the form of DNA or RNA Genetic material in the form of DNA Can only reproduce within a host cell Independent cell division, sexual or asexual No ribosomes

How do viruses differ from prokaryotic and eukaryotic cells?

How are multicellular organisms organised?

● Many cells make up a tissue ● Many tissues make up an organ ● Many organs make up an organ system

define tissues

A group of cells working together to carry out a specific function.

define tissues

A group of cells working together to carry out a specific function.

define organ

A group of tissues working together to carry out a specific function.

Define organ system

A group of organs working together to carry out a specific function

function of lysosomes

Fluid-filled vesicles surrounded by a single membrane, contain enzymes ● Role in phagocytosis, digest unwanted materials in the cytoplasm

define plasmodesmata

Microscopic channels between plant cell walls that facilitate communication and symplastic transport.