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A Level Biology Paper 1 > Cells and Organelles > Flashcards

Cells and Organelles Flashcards

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1
Q

Define Eukaryotic

A

True nucleus
DNA enclosed in a nuclear membrane
Membrane organelles

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2
Q

Examples of eukaryotes

A 
Plants
Animals
Fungi
Algae
Protozoan
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3
Q

Nucleus function

A

Contains DNA which stores genetic information to synthesise proteins
Controls cell activity

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4
Q

Structure of the nucleus

A

Nuclear envelope/double membrane: contains nuclear pores to allow for passage of molecules like mRNA into and out of the cell

Nucleolus: where ribosomal RNA (rRNA) and ribosomal subunits are synthesised in the nucleus (assembled elsewhere)

Chromatin: made of DNA that has been coiled around histones, and supercondenses in cell division to form structures called chromosomes

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5
Q

Mitochondrion function

A

Site of ATP synthesis via aerobic respiration

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6
Q

Structure of mitochondrion

A

Double membrane: inner is highly folded to form cristae which increase the surface area for attachment of ATP synthase

Matrix: a liquid within the inner membrane that contains proteins, lipids, mitochondrial DNA and ribosomes

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7
Q

RER function

A

Rough Endoplasmic Reticulum

Synthesises and transports proteins throughout the cell

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8
Q

RER structure

A

Made from highly folded membranes with 80s ribosomes embedded

Membrane folded into flatterned sacs called cisternae

Joined to the nucleus so easier for mRNA to get into nucleus to make proteins

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9
Q

SER function

A

Smooth Endoplasmic Reticulum

Recombines glycerol and fatty acids to make triglycerides

Packages triglycerides into vesicles and transports them ti the golgi apparatus

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10
Q

SER structure

A

Highly folded membranes with no ribosomes attached

Folded into flatterned sacs called cisternae

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11
Q

Ribosome function

A

Site of protein synthesis from amino acids

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12
Q

Ribosome structure

A

2 subunits containing rRNA and ribosomal proteins

The subunits are a combination of long strands of rRNA dotted with ribosomal proteins

Eukaryotes contain 80s (also 70s in mitochondria or chloroplasts)

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13
Q

Golgi apparatus function

A

Sorts, modifies and packages molecules like proteins and triglycerides into vesicles

Can be used to form lysosomes

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14
Q

Golgi apparatus structure

A

Composed of flattened sacs made of membranes

Sacs are fluid filles and pinch off into smaller sacs at the end (vesicles)

Usually only one in each cell

Well developed in secretory cells because large volumes of molecules must be processed sorted and packaged into vesicles for transport out of cell

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15
Q

Vesicles function

A

Transports molecules around the cell and out of the cell

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16
Q

Vesicles structure

A

Small fluid filled sacs found at the end of the golgi apparatus

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17
Q

Lysosome function

A

Contain the hydrolytic digestive enzymes lysozymes to hydrolyse damaged and worn out components of cells

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18
Q

Lysosome structure

A

Single membrane

No clear internal structure

Contain a large number of hydrolytic enzymes called lysozymes that are kept in an acidic solution and separate from the rest of the cell to prevent organelle digestion

19
Q

Microvilli function

A

Increase surface are of cells

20
Q

Microvilli structure

A

Finger like projections of the cell membrane that increase the surface area for faster absorption of food

Found on epithelial cells in the small intestines

21
Q

Function of centrioles

A

Involved in mitosis to form a network of spindle fibres across the cell onto which the chromosomes attach

Spine fibres pull the chromosomes apart

22
Q

Structure of centrioles

A

Not found in plants

Cylindrical structures found in perpendicular pairs near the nuclear membrane in the cytoplasm

23
Q

Function of the plasmodesmata

A

Allows for substance exchange between adjacent plant cells

24
Q

What are some key differences between plant and animal cells

A

1) Plant has cellulose cell wall/Animal no cell wall
2) Plants have chloroplast present/Animal no chloroplast
3) Plants have large central vacuole/Animal no large central vacuole
4) Plants store carbohydrates as starch/Animals store carbohydrates as glycogen
5) Plants have no centrioles/Animals have centrioles
6) Plants have plasmodesmata/Animals have no plasmadesmata

25
Q

Chloroplast Function

A

Absorb light energy and convert it into chemical energy (done by the chlorophyll and other pigments)
Chemical energy used to make carbs from CO2 and H2O
Which can then be used for respiration or to make other organic molecules to enable growth

26
Q

What’s the structure of chloroplast

A

Double membrane for protection
Granum = Stack of thylakoid membranes
Thylakoid membranes = Contain chlorophyll for photosynthesis
Stroma = Fluid filled part, some of photosynthesis reactions occur here (+enzymes)
Starch grains = Energy storage in plants
DNA and Ribosomes = Have their own DNA and 70s ribosomes to make enzymes needed for photosynthesis

27
Q

How are chloroplast proof of evolution

A

They have 70s ribosomes like prokaryotes

28
Q

Define Prokaryotic

A

Before nucleus
No nuclei or other membrane bound organelles
DNA is circular and does not form chromosomes, floats freely in the cytoplasm and not associated with histones

29
Q

Function of flagella

A

Provides motility

Can have 0,1,2 ….

30
Q

Function of mesosomes

A

Provide a larger surface area for the attachment of respiratory enzymes

31
Q

Function of pilli

A

Help bacteria/prokaryotic cells attach o surfaces

Connect between bacteria, allowing horizontal DNA (plasmid) transfer

32
Q

Function of plasmids

A

Have extra genetic material and genes for antibiotic resistance
Can be transferred between bacteria via pilli

33
Q

Bacterium cell membrane

A

Murein (peptidoglycan)

34
Q

What is the function of the slime capsule

A

Made of secreted polysaccharides
Helps them cling to eachother and to surfaces
Prevents the cell from dying out

35
Q

Contrast prokaryotic and eukaryotic cells

A

<p> Circlular DNA Linear DNA
</p>

<p> Not associated with histones Associated with histones
</p>

<p> No membrane bound organelles Membrane bound organelles
</p>

<p> DNA free floating in cytoplasm DNA in nucleus
</p>

<p> 70s ribosomes 80s (70s in some organelles)
</p>

<p> Capsule and plasmids Neither
</p>

<p> Mesosomes for ATP syntase Mitochondria for ATP synthase
</p>

<p> Murein cell wall No cell wall/Plants cellulose

</p>

36
Q

What is a viruses class

A

No

Acellular

37
Q

Structure of virus

A
  • DNA or RNA that can be single or double stranded
  • That’s surrounded by a protein coat called a capsid
  • Attarchement proteins allow it to bind to host cell
  • Enzyme it uses to replicate its genetic information and insert this into the host cells DNA
38
Q

Explain plant cell walls

A

Cellulose in plant and algae
Very strong because many weak H bonds between fibrils which limit volume of water that can move into cell (prevents osmotic lysis)
Permeable to most molecules unlike cell membrane
Cell qalls of adjacent plant are separated by thin layer called middle lamella which acts to stick walls together with pectin
Plasmodesmata are gaps that allow easy movement of small water soluble molecules and connect cells to cytoplams

39
Q

Why can’t viruses self replicate

A

They have no organelles so unable to replicate independently
They can’t synthesise protein or DNA to make copies of themselves
Need a host to do it for it

40
Q

Advantage of inserting genes into eggs

A

Gene gets into all of orgabism

So gets into cell that it’s meant to (relate to Q)

41
Q

How to prepare mount for microscope

A 
Add drop of water to glass slide
Thin section and place ontop
Stain (with iodine)
Avoid trapping air bubbles
Lower cover slip slowly with mounted needle
42
Q

How does interphase and mitosis produce 2 genetically identical cells

A

DNA replication semiconservative involving complementary based pairing
Two identical sister chromatids
Each moves to opposite poles

43
Q

Why should specimen be thin for light microscope

A

So more light can get through

So fewer cells can be viewed

44
Q

Why does carbon dioxide uptake drop in dark

A

No light no photosynthesis so no need
No diffusion gradient for it to enter the leaf

No diffusion gradient for it to leave due to respiration

A Level Biology Paper 1 (16 decks)

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