Cell Structure Flashcards

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1
Q

What is a eukaryotic cell?

A

Cell that contains DNA in a nucleus and is MEMBRANE-BOUND.

It is MULTICELLULAR.
Animal.
Plant.
Algae.
Fungi.

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2
Q

What is a prokaryotic cell?

A

Cell where DNA is free in the cytoplasm and is NOT membrane-bound.

It is UNICELLULAR.
Bacteria.

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3
Q

What are some examples of eukaryotes?

A

Animal cells
Plant cells
Algae
Fungi

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4
Q

What are some examples of prokaryotes?

A

Bacteria.

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5
Q

What are the differences between eukaryotes and prokaryotes?

A

Eukaryotes =
membrane-bound organelles
multicellular
DNA enclosed in nucleus

Prokaryotes =
not membrane-bound organelles
unicellular
DNA is free in cytoplasm.
Smaller

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6
Q

What is a multicellular organism?

A

Multicellular organisms use many different cells to function.

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7
Q

What is a unicellular organism?

A

Made up of only 1 cell that carries out all of the functions needed by the organism,

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8
Q

What is the cell membrane made out of?

A

Phospholipid bilayer.

Glycolipids
Glycoproteins
Cholesterol

Mainly lipids & protein.

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9
Q

What is the difference between a membrane and a cell-surface membrane?

A

A cell-surface membrane is the membrane surrounding the cell’s surface.
A normal membrane is the membrane around organelles?

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10
Q

What are cells made up of?

A

Organelles.

Remember… Year 9?
Cells, cells, they’re made of organelles!

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11
Q

What are the features of a nucleus?

A

NUCLEOPLASM =
contains chromosomes
Site of DNA synthesis

NUCLEOULUS =
(central region)
assembles ribosomes.

NUCLEAR ENVELOPE =
double membrane w/ nuclear pores to let substances exit/enter cell.

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12
Q

State the relationship between specialised cells and a system.

A

Specialised cells form…

Tissues that perform specific function that form…

Organs made of dif tissue types that form…

Organ systems

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13
Q

What is the function of cell-surface membranes?

A

Controls what molecules enters and leave the cell.

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14
Q

What is the structure and function of mitochondria?

A

= Structure =
Has DOUBLE MEMBRANE.

Inner membrane is folds to form CRISTAE (the inner layer of membrane inside)

Contains SHORT, CIRCULAR DNA.

Fluid MATRIX (gap inside mitochondria) contains enzymes involved in respiration.

= Function =
SITE of AEROBIC RESPIRATION to produce ATP (releases energy)

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15
Q

What is the structure and function of ribosomes?

A

= Structure =
Ribosomes have NO MEMBRANE.

Float freely in cytoplasm or attached to RER.

= Function =
Produces polypeptides from amino acids to form proteins.

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16
Q

What is the structure and function of a cell wall?

A

= Structure =
Made of CELLULOSE in plants & algae.
Made of CHITIN in fungi.
Made of MUREIN in prokaryotes.

= Function =
Supports cell providing rigidity and prevents them losing their shape.

Physical barrier against pathogens.

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17
Q

What organisms contain cell walls?

A

Plants
Bacteria
Algae
Fungi

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18
Q

What is the cell wall in plants made of?

A

Cellulose

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19
Q

What is the cell wall in fungi made of?

A

Chitin

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20
Q

What is the structure and function of the vacuole?

A

= Structure =
Single membrane called TONOPLAST.
Some pigments are found in the vacuole.

= Function =
Temporary food store containing sugars & amino acids.

Absorbs & hydrolyses harmful substances to detoxify cytoplasm.

When vacuole is full of fluid the cell becomes turgid (may burst)

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21
Q

Describe the structure and function of chloroplasts.

A

= Structure =
Contains DOUBLE MEMBRANE.
Small, flattened structure.

THYLAKOID membranes form stacks called GRANA (which contains chlorophyll)

Grana are connected by LAMELLAE (thin, flat pieces of thylakoid membrane)

= Function =
ABSORBS light for photosynthesis to produce carbohydrates.

Photosynthesis can happen in grana or stroma (body)

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22
Q

What key words are associated with chloroplast?

A

Thylakoid membrane

Double membrane

Grana / granum (singular)

Lamellae

Stroma

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23
Q

What key words are associated with the nucleus?

A

Double membrane

Nucleolus

Nucleoplasm

Nuclear envelope

24
Q

What are the key words associated with mitochondria?

A

Matrix

Cristae

Circular DNA

Double membrane

25
Q

What are the key words associated with rough endoplasmic reticulum?

A

Enclosed in a fluid-filled space.

HAS ribosomes.

Folds polypeptides into final 3D protein shape.

26
Q

What are the key words associated with smooth endoplasmic reticulum?

A

Synthesis, processes, stores.

NO ribosomes

Steroids & lipids

Lipid synthesis

27
Q

What does RER stand for?

A

Rough endoplasmic reticulum

Endon = within
Plasma = anything formed/moulded
Reticulum = small net

28
Q

What does SER stand for?

A

Smooth endoplasmic reticulum.

29
Q

What is the cell wall in prokaryotes made of?

A

Murein

30
Q

What organelles contain DNA?

A

Nucleus
Mitochondria
Chloroplast

31
Q

What feature makes an endoplasmic reticulum rough?

A

Having ribosomes.

32
Q

Describe and explain the function of rough endoplasmic reticulum.

A

DESCRIBE…
RER is a system of membranes enclosing a fluid filled space.
Surface covered in RIBOSOMES.

EXPLAIN…
RER folds polypeptides into proteins made in ribosomes.

33
Q

Describe and explain the function of smooth endoplasmic reticulum.

A

DESCRIBE…
Has NO ribosomes bound.

EXPLAIN…
Involved in synthesising, processing and storing molecules such as steroids (e,g, testosterone/oestrogen) and other lipids.

Stores lipids basically that combine with proteins to form lipoproteins.
Lipid synthesis.

34
Q

Describe the structure and function of the golgi apparatus.

A

= Structure =
Group of fluid-filled membrane-bound FLATTENED discs.

= Function =
MODIFIES proteins - making them into glycoproteins/lipoproteins.

PACKAGES proteins into vesicles to transport them in and out of cell.

MODIFIES triglycerides.

35
Q

What is the structure and function of lysosomes?

A

= Structure =
Round organelles surrounded by single membranes. It’s literally a ball that transports.

Type of Golgi vesicle.

= Function =
Contains ENZYMES to breakdown substances (e.g. worn out components of the cell)

36
Q

What is a lysozyme?

A

Enzyme that breaks down some bacterial cell walls.

37
Q

Describe how a lipoprotein is formed and transported out of the cell. [3 marks]

A

1# Ribosomes assemble amino acids to form polypeptides.

2# RER folds polypeptides into shape to form protein.

3# Lipids in SER and proteins in RER meet at Golgi apparatus.

4# Combines lipid & proteins to form lipoprotein.

5# Vesicle forms from Golgi which contains lipoprotein.

6# Vesicle travels to and fuses with plasma membrane. Exocytosis occurs.

38
Q

What is exocytosis?

A

When molecules move out of the cell.

39
Q

Describe the structure and function of a cell-surface membrane.

A

= Structure =
“Fluid mosaic” phospholipid bilayer with extrinsic & intrinsic proteins embedded.

= Function =
Separates cytoplasm from extracellular environment.

SELECTIVELY PERMEABLE to regulate transport of substances.

Involved in cell SIGNALLING / cell RECOGNITION.

40
Q

Name one other substance other than the phospholipid bilayer that makes up a cell-surface membrane.

A

Glycolipids

Glycoproteins

Cholesterol

41
Q

Explain the role of cholesterol in the cell-surface membrane.

A

A steroid molecule that connects with phospholipids and reduces fluidity of cell.

42
Q

Explain the role of glycolipids in the cell-surface membrane.

A

Cell signalling & cell recognition (antigens)

43
Q

Explain the role of glycoproteins in the cell-surface membrane.

A

Cell signalling & cell recognitions.
&
Binding cells together.

44
Q

Describe the function of the nucleus.

A

Controls cell function =
gene expression determines…

specialisation,
mitosis,
site of mRNA transcription,
replication.

Contains DNA coiled around CHROMATIN to form chromosomes.

45
Q

How are chromosomes formed?

A

DNA coils around CHROMATIN.

46
Q

Describe the structure and function of ribosomes.

A

= Structure =
DO NOT have a membrane.
Float freely in cytoplasm or attached to RER.

= Function =
Where amino acids are joined together to make proteins (e.g. protein synthesis)

47
Q

Explain some common cell adaptations.

A

Folded membrane / MICROVILLI =
Increases surface area for diffusion.

Many MITOCHONDRIA =
large amounts of ATP for active transport.

Walls 1 cell thick =
to reduce distance of diffusion pathway.

48
Q

Is a virus particle larger or smaller than a bacterial cell?

A

Smaller.

Viruses are much smaller than bacteria.

49
Q

Explain whether viruses are considered cells.

A

Viruses are NOT cells.

Because they cannot reproduce independently.
They can only reproduce inside a host cell using their enzymes.

50
Q

Describe how a virus replicates. [3 marks]

A

1# Virus ATTACHES to the protein markers on a host cell using attachment proteins.

2# Virus INJECTS its genetic material into the HOST cell.

3# Host cell transcribes / translates the viral genes.

4# Protein forms NEW virus particles.

5# Virus particles BURST out of host cells and the host cell is destroyed.

51
Q

Describe the structure and function of a virus. [4 marks]

A

A virus consists of…

Genetic material =
ALL viruses contain DNA / RNA.

Capsid =
Protein structure which contains the genetic material.

Attachment proteins =
Allow virus particles to attach and enter host cell.

Lipid envelope =
SOME viruses are surrounded by a lipid envelope formed from the host cell membrane.

52
Q

What is the DNA in eukaryotes coiled around?

A

Histone proteins

53
Q

How does DNA become coiled?

A

DNA coils around HISTONE proteins which makes the structure coiled.
This makes DNA compact and fit a lot of genetic information in a small volume.

54
Q

What features do prokaryotic cells contain?

A

Plasmids
Single DNA molecule
Flagella
Slime capsule

Ribosomes
Cell membrane
Cell wall

55
Q

Describe the structure and function of bacteria.

A

Plasmids =
Contains genetic information and codes for antibiotic resistance.

Single DNA molecule =
DNA loop - stores genetic info.

Flagella =
Helps with movement.

Slime capsule =
Outermost layer - sticks to cells - also protects cell from harm/chemicals.

Pili =
Some bacteria have pili which helps stick to surfaces.

56
Q

Do ribosomes count as organelles?

A

No

because they are not membrane-bound.