Cell Structure Flashcards

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1
Q

Two types of cells

A
  • Eukaryotes - Cells with a nucleus and organelles

- Prokaryotes - Cells with no nucleus (bacteria)

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2
Q

Organelles

A

Self-contained structures inside cells. All have their own membranes

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3
Q

Nucleus

A
  • Contains chromosomes (genes made of DNA which code for protein synthesis)
  • Separated from the cytoplasm by a nuclear envelope and its continuous with Rough ER
  • The envelope is made of a double membrane containing small holes called Nuclear Pores (100nm)
  • Nuclear Pores allow the transport of mRNA in and out of the nucleus
  • Nucleolus - makes ribosomal RNA (rRNA) and ribosomes
  • Chromatin - protein (histone) + DNA
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4
Q

Endoplasmic Reticulum (ER)

A
  • Its a series of tubes (membranes) running through the cytoplasm which distributes substances through the cell. There are 2 types:
  • Rough ER - has ribosomes (join amino acids) - makes proteins. Found in cells that are making proteins for export (enzymes, hormones, structural proteins, antibodies)
  • Smooth ER - no ribosomes attached, makes detoxifies cell poisons, numerous in the liver
  • ER is abundant in secretory cells
  • rER puts the proteins into shuttle vesicles to transport them to the Golgi Body
  • Structure - stack of cisternae or flattened sacs
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5
Q

Golgi Apparatus/Body

A
  • Proteins from rER to the Golgi body which modifies it: Adds on carbohydrate group = glycoprotein, Folds it up-Enzymes, makes lysosomes
  • Secretory vesicles bud of Golgi body and fuse with the cell membrane releasing the glycoprotein outside the cell. This is called exocytosis
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6
Q

Lysosomes

A

-Lysosomes are made by the Golgi body (and rER)
-Contain enzymes
They are used for:
1) Intracellular digestion
2) Breaks down worn out organelles
3) Breaks down cell after its death (Autolysis)
4) Breaks down whole organism - metamorphosis - also enzymes are secreted for extracellular digestion

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7
Q

Mitochondria

A
  • Site of respiration - releases energy so requires oxygen and glucose; produces carbon dioxide and water
  • Makes ATP (Adenosine Triphosphate) from ADP (Adenosine Diphosphate)
  • Double membrane and inner membrane folded - cristae provides large surface area for enzyme attachment
  • More mitochondria in active cells i.e. muscle and liver
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8
Q

Why do Mitochondria have______?

A
  • Ribosomes - to make the enzymes (proteins) for respiration
  • DNA - contain the genetic code for protein - enzyme: to replicate themselves especially when the cell becomes more active
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9
Q

Ribosomes

A

-Smallest organelle (20nm) last to be sedimented in a centrifuge
-Found in both prokaryotic and eukaryotic cells (more)
-Site of protein synthesis - join amino acids together to form polypeptide
-Two types:
>70s in prokaryotic cells, mitochondria & chloroplast
>80s in eukaryotic cells

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10
Q

Microvilli

A

Finger like projections on cell surface increase surface area for absorption

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11
Q

Centriole - not in plants

A

Structure:
-a centriole is a small set of microtubules (9) arranged in at right angles to each other and located just outside the nucleus
Function:
-Forms the spindle during cell division

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12
Q

Vacuoles - not found in animal cells

A
  • Structure - Fluid filled sac surrounded by single membrane called the tonoplast.
  • Function - Contains cell sap, Provides support/turgor to cell
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13
Q

Chloroplasts - not found in animal cells

A

-Structure:
>Double membranes
>Inner membrane Is folded into flattened sacs thylakoids that are stacked into grana (one granum) - large surface area for chlorophyll attachment
>Chlorophyll - green pigment that absorbs light energy
>Lipid and starch grain - store products of photosynthesis
>DNA - to replicate themselves
>Ribosomes - to make enzymes for photosynthesis reaction
-Function:
>Absorbs light for photosynthesis - produce glucose and oxygen from CO2 and water

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14
Q

Cell Wall

A

-Structure:
>Made of cellulose (polysaccharides) in plant cells; that are held in microfibrils and embedded in pectin
-Function:
>Support - prevents cell bursting when turgid
>Transport - gaps between cellulose makes it fully permeable to substances
>Communication - between cells - have holes called pits that contain plasmodesmata

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15
Q

Plasmodesmata

A
  • Structure - They are microscopic channels which traverse the cell walls of plant cells and some algal cells
  • Functions - Allow transport and communication between cells
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