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Biology > Cell structure > Flashcards

Cell structure Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the structure of the nucleus?

A

Nuclear envelope - double membrane
Nuclear pores
Nucleoplasm - granular, jelly-like material
Chromosomes - protein-bound, linear DNA
Nucleolus - small sphere inside which is the site of rRNA production and makes ribosomes

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2
Q

What is the function of the nucleus?

A

Site of DNA replication and transcription
Contains the genetic code for each cell

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3
Q

What is the structure for the rough and smooth endoplasmic reticulum?

A

Both have folded membranes - cisternae

Rough has ribosomes on cisternae

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4
Q

What is the function of the endoplasmic reticulums?

A

RER - protein synthesis
SER - synthesis and store lipids and carbohydrates

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5
Q

What is the structure of the Golgi apparatus and vesicles?

A

Folded membranes making cisternae
Secretary vesicles pinch off from the cisternae

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6
Q

What is the function of the Golgi apparatus and vesicles?

A

Add carbohydrates to proteins - glycoproteins
Produce secretory enzymes
Transport, modify and store lipids + proteins
Form lysosomes

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7
Q

What is the structure of lysosomes?

A

Contain powerful hydrolytic enzymes (proteases, lipases, carbohydrase’s and nucleases)

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8
Q

What is the function of lysosomes?

A

Fuses with phagosome (phagolysosome) and release hydrolytic enzymes
Destroy damaged organelles and cells
Exocytosis - release enzymes to outside of cell to destroy material
Completely break down dead cells (autolysis)

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9
Q

What is the structure of mitochondria?

A

Double membrane
Inner membrane - cristae
Fluid centre - matrix
Loop of mitochondria DNA

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10
Q

What is the function of mitochondria?

A

Site of aerobic respiration and ATP production
DNA codes for enzymes needed for respiration

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11
Q

What is the structure of ribosomes?

A

Small, made up of two sub-units of protein and rRNA
80s - large, eukaryotic cells
70s - small, prokaryotic cells, mitochondria and chloroplasts

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12
Q

What is the function of ribosomes?

A

Site of protein synthesis

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13
Q

What is the structure of a vacuole?

A

Filled with fluid surrounded by a single membrane - tonoplast

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14
Q

What is the function of a vacuole?

A

Makes cells turgid - provide support
Temporary store of sugars + amino acids

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15
Q

What is the structure of chloroplasts?

A

Surrounded by double membrane
Thylakoids (folded membranes embedded with pigment)
Fluid filled stroma has enzymes - photosynthesis

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16
Q

What is the function of chloroplasts?

A

Site of Photosynthesis

17
Q

What is the structure of a cell wall?

A

plants - microfibrils of cellulose
fungi - chitin, nitrogen containing polysaccharide

18
Q

What is the function of a cell wall?

A

Provide structural strength to the cell

19
Q

What is the structure of the cell membrane?

A

Selectively permeable
Phospholipid bilayer

20
Q

What is the function of the cell membrane?

A

Controls the entrance and exit of molecules

21
Q

What do all prokaryotic cells contain?

A

Cytoplasm, ribosomes, plasma membrane, DNA

22
Q

What is the equation for magnification?

A

actual size = image/magification

23
Q

What are the features of light microscopes?

A

magnification = x2000
resolution = 200nm

visible light passes through specimen
cheap, can study living cells
limited magnification and resolution, thin specimen only
2D image

24
Q

What are the features of transmission electron microscopes?

A

magnification = x500 000
resolution = 0.05-0.2nm

electromagnets focuses a beam of electrons - transmitted through specimen
denser parts absorb more electrons
higher resolution allows internal structure to be seen
no live specimen due to vacuum - removes all water
2D

25
Q

What are the features of a scanning electron microscope?

A

magnification = x250 000
resolution = 0.5nm

scans beam of electrons across specimen
thick or 3D specimen used
can’t observe live specimen, no colour, lower resolution
3D

26
Q

What is cell fractionation?

A

Used to isolate different organelles to study them

1) homogenisation
2) ultracentrifugation

27
Q

What solution do cells need to be in for cell fractionation?

A

Cold - reduce enzyme activity, cells break open enzymes released may damage organelles

Isotonic - same water potential to prevent osmosis - cells don’t shrivel or burst

Buffered - pH buffer prevents damage

28
Q

What is homogenisation?

A

Cells broken up (homogenised) using a blender in cold, isotonic and buffered solution

Solution is filtered to remove large cell debris

29
Q

What is ultracentrifugation?

A

Filtered solution is spun at different speeds in a centrifuge

Organelles separate according to densities

30
Q

What is differential centrifugation?

A

Centrifugal forces causes most dense organelles to from at the bottom

Speed increases + each time the super latent (liquid) is removed, leaving a pellet of organelles

31
Q

What is the density order of organelles?

A

Nuclei
Chloroplast
Mitochondria
Lysosomes
Endoplasmic reticulum
Ribosomes

32
Q

What are the three stages of cell division?

A

Interphase
Mitosis
Cytokinesis

33
Q

What are the stages of mitosis?

A

prophase, metaphase, anaphase and telophase

34
Q

What happens in prophase?

A

Chromosomes condense (shorter + thicker)
2 sister chromatids joined by a centromere
Nuclear envelope breaks down
Centrioles move to opposite poles forming spindle network

35
Q

What happens in metaphase?

A

Chromosomes align along equator
Spindle fibres attach to chromosomes by centromeres

36
Q

What happens in anaphase?

A

Spindle fibres contract –> pull chromatids to opposite poles
Centromere divides

37
Q

What happens in telophase?

A

Chromosomes uncoil (longer/thinner)
Nuclear envelope reforms (2 nuclei)
Spindle fibres and centrioles break down

38
Q

What happens in cytokinesis?

A

Cell divides into two - creates new genetically identical cells

39
Q

What is mitotic index?

A

percentage/measure of cells undergoing mitosis

Biology (3 decks)

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