Cell Structure & Diversity 4 - Photosynthesis & The nucleus Flashcards Preview

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Flashcards in Cell Structure & Diversity 4 - Photosynthesis & The nucleus Deck (72)
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1
Q

What is the equation for photosynthesis?

A

6CO2 + 6H2O&raquo_space;»>plant»»>light»»> C6H12O6 + 6O2

2
Q

What are chloroplasts?

A

The organelle where photosynthesis occurs

3
Q

What are chloroplasts similar to?

A

Mitochondria

4
Q

What is the structure of a chloroplast?

A

They have an outer and inner membrane which contains thylakoids. The thylakoid membrane encloses the thylakoid space and outside of the thylakoids is the stroma. Also contains DNA and ribosomes

5
Q

Where does the light reaction take place?

A

The thylakoid membrane which has a large surface area

6
Q

Where does carbon fixation occur?

A

In the stroma

7
Q

What happens in the light reaction?

A

Light energy is captured and converted into chemical energy using pigment and protein complexes embedded in the thylakoid membrane.

8
Q

What is the structure of the thylakoid membrane?

A

Lipid bilayer

9
Q

What are photosystems?

A

protein complexes which contain chlorophyll

10
Q

What is the function of chlorophyll?

A

To absorb light energy

11
Q

What does light energy produce?

A

High energy electrons

12
Q

What do high energy electrons do?

A

Travel through the photosynthetic electron transport chain

13
Q

What photosystem do electrons first go to?

A

Photosystem 2

14
Q

How do the electrons travel?

A

In pairs

15
Q

Where are the electrons obtained from?

A

The splitting of water

16
Q

What happens as a result of water splitting?

A

Oxygen is released as a byproduct

17
Q

What happens at photosystem 1?

A

The electrons gain energy from light

18
Q

Where is the second location electrons move to?

A

Cytochrome complex

19
Q

What happens at the cytochrome complex?

A

Electrons lose energy which is then used to pump protons across the membrane into the thylakoid space

20
Q

Where do electrons move after the cytochrome complex?

A

Photosystem 1

21
Q

What happens at Photosystem 1?

A

More light energy is absorbed by the chlorophyll and transferred to the electrons to make high energy electrons which are held in NADPH carriers.

22
Q

What does the cytochrome complex create?

A

The proton gradient in the thylakoid space so that chemiosmosis can occur through the ATP synthase to make ATP

23
Q

What are the outputs of the photosynthetic electron transport chain?

A

ATP, NADPH and oxygen

24
Q

What is ATP and NADPH used for?

A

The Calvin cycle only

25
Q

What occurs during the Calvin cycle?

A

ATP and NADPH produced in the light reaction are used to fix CO2 and produce carbohydrate

26
Q

Where does the Calvin cycle occur?

A

In the stroma of the chloroplasts

27
Q

What occurs during fixation?

A

CO2 binds with a 5 carbon molecule to make 2 three carbon molecules which uses no energy

28
Q

What occurs during reduction?

A

Low energy 3 carbon molecules are converted into high energy 3 carbon molecules which requires ATP and NADPH. The 3 carbon sugar leaves the cycle to form glucose

29
Q

What happens during regeneration?

A

The 3 carbon molecules are converted back into 5 carbon molecules which can be used during fixation

30
Q

What is the output the Calvin cycle?

A

A 3 carbon sugar which is converted into glucose. Glucose is then broken down during respiration in the mitochondria

31
Q

How big is the nucleus?

A

5-10 micrometers making it the most prominent organelle in eukaryotic cells

32
Q

How many nuclei are in a cell?

A

Most cells contain one but they can have more or even none

33
Q

What is contained in the nucleus?

A

Most of the cells genes but some are also found in the mitochondria and chloroplasts

34
Q

What is the function of the nucleus?

A

A place to hold inherited genetic information and Aldo the control centre of cells which makes sure the DNA isn’t damaged and by turning genes on and off it can control what the cell does

35
Q

What is the nuclear envelope?

A

The structure which surrounds the nucleus

36
Q

What is the structure of the nuclear envelope>

A

Double membrane which are both composed of phospholipid bilayers

37
Q

What is the nuclear envelope continuous with?

A

The endoplasmic reticulum meaning that the space between the two layers is continuous with the lumen

38
Q

What does the nuclear pore complex do?

A

Control the movement of molecules out of, or into the nucleus

39
Q

What moves out of the nucleus through the nuclear pore complex?

A

mRNA, tRNA and ribosomal subunits

40
Q

What is then function of mRNA?

A

Messenger RNA carries information from a gene

41
Q

What is tRNA and ribosomal subunits needed for?

A

Building proteins

42
Q

What moves into the nucleus through the nuclear pore complex?

A

control signals, building materials and energy

43
Q

Why are control signals needed?

A

To know when to turn a gene on or off

44
Q

What are building materials needed for?

A

RNA

45
Q

What is energy needed for?

A

Chemical synthesis

46
Q

What is found inside then nuclear envelope?

A

The nuclear membrane lines the inner surface of the nuclear membrane

47
Q

What is the structure of the nuclear lamina?

A

Intermediate filaments (lamina) which form a network and anchor nuclear pores

48
Q

What is the function of the nuclear lamina?

A

Maintains the shape of the nucleus and helps organise packing of DNA within the nucleus

49
Q

What is the nucleolus?

A

A prominent nuclear structure within non-dividing cells

50
Q

How many nucleoli are present in a nucleus?

A

May be one or more than one depending on the species and which stage of the cell cycle it is at

51
Q

What is the function of the nucleolus?

A

Responsible for making ribosomal RNA which combines with proteins to produce ribosomes

52
Q

What is a feature of structures within the nucleus?

A

They aren’t fixed, they change based on what the cell is doing

53
Q

What is DNA?

A

A nucleotide polymer

54
Q

How much DNA is in each human cell?

A

2.5 m which is 250,000 times the diameter of the nucleus

55
Q

How must DNA be arranged in the nucleus?

A

Very well packed but also accessible to allow for transcription to occur

56
Q

What is the diameter of DNA?

A

Around 2 nanometres

57
Q

What does DNA do first to fit into the nucleus?

A

Interacts with specific proteins called histones (H2A, H2B, H3 and H4). Two of each kind (8 in total) cluster together and then DNA wraps around them

58
Q

What is the cluster of histones called?

A

Nucleosome

59
Q

What is the size of a nucleosome?

A

10nm in diameter

60
Q

What happens after a nucleosome has formed?

A

DNA further interacts with another histone (H1) causing the 10nm fibre to form a 30nm fibre

61
Q

What happens with 30nm fibres?

A

They are supercoiled tighter to form 300nm fibres

62
Q

What happens with 300nm fibres?

A

They are coiled even more to form metaphase chromosomes during cell division

63
Q

What is a karyotype?

A

How chromosomes are displayed which can be used to screen chromosomal defects

64
Q

How is euchromatin shoes in images?

A

Light patches

65
Q

What is the features of euchromatin?

A

It is less dense and contains genes which are currently being used by the cell

66
Q

How is heterochromatin shown in images?

A

Dark patches

67
Q

What is the features of heterochromatin?

A

It is more dense and contains genes which aren’t being used by the cell so leaves more space for genes which are being used by the cell

68
Q

What is the relationship between euchromatin and heterochromatin?

A

Dynamic

69
Q

What is the location of chromosomes within the nucleus during interphase?

A

Not random

70
Q

What is the function of the nuclear lamina with relation to chromosomes?

A

Keeps them in position

71
Q

What shows the location of each chromosome?

A

Coloured tags, pairs aren’t generally found together

72
Q

What is a feature of cancer cells?

A

Their chromosomes are very disorganised