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Biology > Cell Structure > Flashcards

Cell Structure Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the four types of microscopes?

A

light microscopes, transmission electron microscopes, scanning electron microscopes and laser scanning confocal microscopes

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2
Q

adv and dsv of light microscope

A

bad resolution because of long light wavelength
living samples can be examined and a colour image can be seen

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3
Q

how does transmission electron microscope work

A

high magnification and resolution as electron gun creates electron beam which is focused by an electromagnet which then passes through the thin layer of sample to create a 2d image. Some parts of the sample absorbs the electron making them darker

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4
Q

how does a scanning electron microscope work

A

high magnification and resolution. sample doesn’t have to be thin.
electrons bounce off the surface of the sample based on the contours to create a 3d image

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5
Q

how does a laser scanning confocal microscope work

A

high resolution and 3d imaging
a laser light with a high light intensity is used to illuminate sample that has been stained with a fluorescent dye

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6
Q

resolution definition

A

the minimum distance between two objects where they can still be distinguished as separate. resolution is determined by wavelength of either light or beam of electrons depending on the microscope used

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7
Q

magnification definition

A

how many times larger the image is compared to the object

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8
Q

what are the four types of slide preparation for light microscopes

A

dry mount, wet mount, squash slide and smear slide

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9
Q

what is dry mount prep

A

when a thin slice or whole specimen is viewed with a cover slip on top

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10
Q

what is wet mount prep

A

when water or a stain is added to a specimen before putting the cover slip on with a mounted needle to prevent air bubbles

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11
Q

what is squash slide prep

A

are wet mounts however you push down on the cover slip to squash sample to make it thinner to enable light to pass through

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12
Q

what is smear slide prep

A

use the edge of another slide to smear the sample across to create a smooth thin evenly distributed layer of sample. place a cover slip on top. e.g. examining blood cells

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13
Q

what is differential staining

A

the use of many chemical stains being used to stain different parts of a cell in different colours

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14
Q

how does differential staining work

A

the positively charged stains (crystal violet or methylene blue) are attracted to and stain negatively charged components of the cell.
the negatively charged stains (nigrosin and congo red) can’t enter the cells as cytosol (liquid part of cytoplasm) repels them creating a stained background so the unstained cells stand out

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15
Q

what is gram staining used for

A

used to identify types of bacteria.

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16
Q

what are the stains used in gram staining

A

crystal violet and safranin

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17
Q

how does gram staining work

A

crystal violet is added then iodine to fix the stain. alcohol is used to wash away any stain that didn’t bind. gram positive bacteria turn purple/blue as they have a thick peptidoglycan cell wall which absorbs dye. gram negative bacteria don’t absorb the dye as they have thin cell walls that don’t retain the dye. So safranin is used as a counter stain turning them red.

18
Q

why do electron microscopes have a high resolution

A

because they have a short wavelength

19
Q

how are the images created in electron microscopes

A

an electromagnet focuses the beam of electrons to create image

20
Q

why can only non-living samples be examined in an electron microscope

A

electrons are absorbed by air so the sample has to be in a vacuum so that the air doesn’t absorb the electrons. living things can’t survive in a vacuum

21
Q

what are the 13 organelles in a eukaryotic cells

A

cell-surface membrane, nucleus, mitochondria, choroplasts, golgi apparatus and golgi vesicles, lysosomes, cytoskeleton, centriole, flagella, cilia, ribosomes, rough and smooth endoplasmic reticulum and cell wall

22
Q

what does the nucleus contain

A

has a nuclear envelope surrounding it with a double membrane structure. has nuclear pores for the mRNA to move out of it. The DNA wraps around the proteins creating chromosomes, linear in shape.
nucleolus- small sphere inside where rRNA and ribosomes are created.

23
Q

function of nucleus

A

-site of DNA replication and making mRNA
-contains genetic code for each cell
-site of ribosome synthesis in the nucleolus

24
Q

what is flagella

A

found on some eukaryotic cells
whip like structure
used for mobility

25
Q

what is cilia

A

hair like projections
either stationery or mobile
mobile cilia help sweep substances along
stationery cilia are used in sensory organs (nose)

26
Q

what are centrioles

A

made of microtubules
they are in pairs to form a centrosome
produces spindle fibre which organises chromosomes in cell division

27
Q

What is the cytoskeleton, and its role in cells?

A

The cytoskeleton is a network of fibers providing mechanical strength, maintaining cell shape, and holding organelles in place. It includes microfilaments, microtubules, and intermediate fibers.

28
Q

What is the endoplasmic reticulum, and its two types?

A

The endoplasmic reticulum (ER) consists of folded membranes called cisternae. Rough ER (RER) has ribosomes and is involved in protein synthesis, while smooth ER (SER) synthesizes lipids and carbohydrates.

29
Q

What is the Golgi apparatus’s function?

A

The Golgi apparatus processes, modifies, and packages proteins, transports/stores lipids, and creates lysosomes. Secretory vesicles release proteins via exocytosis.

30
Q

What are lysosomes and their function?

A

Lysosomes are vesicles containing digestive enzymes that hydrolyze bacteria, break down dead cells, and release their contents outside the cell after digestion.

31
Q

What is the structure and function of mitochondria?

A

Mitochondria have a double membrane with folded inner membranes (cristae) and a fluid center (matrix). They are the site of aerobic respiration and ATP production, containing their own DNA and ribosomes.

32
Q

What are ribosomes and their function?

A

Ribosomes are made of two subunits of protein and RNA. In eukaryotic cells, they are 80S ribosomes, and in prokaryotes, they are smaller 70S ribosomes. They are the site of protein synthesis.

33
Q

What are chloroplasts, and where are they found?

A

Chloroplasts are found in plant cells. They have a double membrane, thylakoids (stacked into grana), and fluid (stroma) for photosynthesis.

34
Q

What are the differences in cell walls between plants and fungi?

A

Plant cell walls are made of cellulose for structural strength, while fungal cell walls are made of chitin, a nitrogen-containing polysaccharide.

35
Q

What is the plasma membrane and its function?

A

The plasma membrane is made of a phospholipid bilayer with embedded proteins and cholesterol. It controls what enters and exits the cell and regulates the permeability.

36
Q

What is the pathway for protein production and secretion?

A

Proteins are synthesized in the RER, folded and packaged into vesicles, sent to the Golgi apparatus for modification, and transported in vesicles to the cell membrane for exocytosis.

37
Q

What are the main differences between prokaryotic and eukaryotic cells?

A

Prokaryotic cells are smaller, lack membrane-bound organelles, have circular DNA (not in a nucleus), 70S ribosomes, and a cell wall made of murein.

38
Q

What are plasmids, and where are they found?

A

Plasmids are additional loops of DNA in prokaryotes, carrying genes like antibiotic resistance. Not all bacteria have plasmids, and they vary in number.

39
Q

What is the function of a capsule in bacteria?

A

The capsule is a slimy layer made of protein that prevents desiccation and helps hide the bacteria from the host’s immune system by covering antigens.

40
Q

What is the role of the flagellum in bacteria?

A

The flagellum is a rotating structure used for bacterial movement. Some bacteria have one or multiple flagella, while others may have none.

Biology (7 decks)

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