Lecture 5&6 - Cell Structure & Function Flashcards

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1
Q

What is the most prominent structure in eukaryotic cells?

A

Nucleus

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2
Q

Where is rRNA synthesised, precisely

A

Nucleolous

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3
Q

What is the role of the nuclear pores?

A

allow exchange of material between the nucleus and cytoplasm

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4
Q

What is chromatin?

A

Uncondensed form of DNA associated with histone proteins (in eukaryotes) and contains some RNA

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5
Q

how many layers of phospholipids does the nuclear membrane have?

A

4 (2 bilayers) It is a double membrane

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6
Q

What is the nuclear pores lined up with?

A

a complex of 8 proteins

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7
Q

What is the analog of cytoplasm in the nucleus?

A

Nucleoplasm

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8
Q

What is the function of genes?

A

Small sections of DNA that usually code for proteins, sometimes RNA(rRNA)

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9
Q

What is the unit of heredity?

A

genes

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10
Q

What are the differences in the structure of free and bound ribosomes?

A

there is no difference in structure

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11
Q

What is the function of free ribosomes?

A

make proteins that function in the cell (work Intracellularly) Eg; enzymes that catalyze first steps of sugar breakdown

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12
Q

what is the relation between protein synthesis and ribosomal count?

A

directly proportional

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13
Q

What are the structural differences between ER and Golgi body?

A
  • ER is continuous with nucleus, Golgi body is NOT
  • ER are physically connected, Golgi body has separate stacks of 3-20 cisternae (both Have cisternae)
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14
Q

Describe the steps of protein synthesis

A
  • mRNA is synthesised from DNA in the nucleus
  • mRNA exits via nuclear pores to the ribosome
  • at ribosome mRNA contains the code to make proteins while tRNA comes to the ribosome with the amino acid corresponding to the codon (triplet)-
  • polypeptide chain stops building when STOP codon is reached
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15
Q

describe the steps of ribosomal synthesis

A
  • rRNA is synthesised in the nucleolous using DNA
  • Combine with protein molecules imported from cytoplasm, now exist as subunits
  • small and large subunits exit the nucleus via nuclear pores
  • Small and large subunits combine in the cytoplasm
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16
Q

What are the functions of the smooth ER?

A
  • Metabolism of carbohydrates
  • synthesis of lipids (including phospholipids and steroids)
  • Detoxification of drugs and poison
  • storage of Ca2+

*Actual function in the cell depends on requirement and tissue function eg; in liver, detoxification

17
Q

How does the ER grow?

A

by adding membrane proteins and phospholipids into it’s own membrane

18
Q

Describe the ER

A
  • the membrane factory of the cell
  • Consists of flattened sacs called cisternae
  • interconnected tubules( even rough and smooth)
  • Continuous with nuclear membrane
  • has a space in middle called ER lumen or cisternal space
19
Q

which chromosome is larger, X or Y

A

Female X is larger

20
Q

what is the function of the Golgi apparatus?

A
  • Modification of products coming from ER such as proteins and phospholipids eg; modification of first carbohydrates attached to protein
  • Removes sugar monomers and substitutes others
  • makes its own polysaccharides
  • may even modify lysosomes in animal cells
21
Q

What are lysosomes ?

A

Membranous sac of hydrolytic enzymes that an animal cells use to digest macromolecules Plant cells do not have lysosomes

have very low PH

help out in phagocytosis in cells such as macrophages

22
Q

What is autophagy?

A

recycling cell’s own organic material using lysosomes

23
Q

Which face of the Golgi apparatus points towards the ER?

A

Cis face