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Cell Biology > Cell Biology Test 1.2 (prokaryotes and eukaryotes) ✅ > Flashcards

Cell Biology Test 1.2 (prokaryotes and eukaryotes) ✅ Flashcards

1
Q

What is the bacterial genome composed of?

A

single circular DNA molecule

some exceptions exist, ie. vibrio cholera with 2 dissimilar chromosomes.

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2
Q

What information does the bacterial genome hold?

A

directions for all necessary functions to maintain a functional and self-replicating cell.

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3
Q

What is in prokaryotic cells, that is similar to histones in eukaryotic cells?

A

nucleoid associated proteins

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4
Q

State the differences between eukaryotes and prokaryotic DNA.

A

Prokaryotes:
- not membrane bound
- nucleoid
- flows freely in the cytoplasm
- only 1
- circular
- no histones or introns
- has nucleoid assosiated proteins

Eukaryotes:
- membrane bound organelle
- more than one (chromosomes)
- located in the nucleus
- linear
- histones and introns

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5
Q

What is the function fo a genome?

A

it directs all growth and processes necessary to maintain a functional, self replicating system

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6
Q

What are plasmids?

A

small, usually circular, covalentry closed, double starnded DNA molecules

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7
Q

How do plasmids replicate?

A

replicate independent of the chromosome

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8
Q

What are the two types of plasmids?

A

TRANSMISSIBLE: transferred by conjugation
NON TRANSMISSIBLE: do not contain transfer genes

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9
Q

What are the key functions of plasmids?

A

1) antibiotic resistance
2) resistance to heavy metals
3) UV resistance
4) exotoxins
5) bacteriocins
6) pilli

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10
Q

What are transposons?

A

jumping genes.
- pieces of DNA that move readily from one site to another.
- jump between the DNA of bacteria, plasmids and bacteriophages.

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11
Q

What are the two ways of transposition?

A

1) Direct transposition: inserted into new site without replication
2) Replicative transposition: replicate their DNA and then insert the new copy into another site.

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12
Q

What is the nucleoid?

A

The region within a prokaryote where the genetic material is located.

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13
Q

What is a prokaryote?

A

An UNICELLULAR organism with no membrane-bound organelles.

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14
Q

In what forms does DNA exist in eukaryotes?

A

1) Nucleus
2) Mitochondria
3) Chloroplasts

all have double membranes

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15
Q

Explain mitochondrial DNA.

A
  • small
  • circular
  • encodes for proteins
  • allows pathways to produce energy (cellular respiration)
  • mitochondrial DNA is inherited from the mother
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16
Q

how many genes exist in mitochondrial DNA?

A

around 37 genes.
rRNA < proteins < tRNA

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17
Q

Explain chloroplast DNA.

A
  • small
  • circular
  • allows for photosynthesis
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18
Q

State the components of the nucleus.

A
  • nuclear membrane
  • nucleolus
  • nucleoplasm
  • inner membrane
  • outer membrane
  • nuclear pore
  • chromatin
  • rough ER surrounding
  • nucleoporins
  • ribosomes (on the surrounding rough ER)
  • importin
  • nuclear lamin
  • lamins
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19
Q

State the two main function of the nucleus.

A

1) storage of genetic material.
2) protein synthesis (transcription)

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20
Q

State the function of nucleoporins.

A
  • control the entry and exit from the cell
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21
Q

How do the nucleoporins look?

A

they have eight fold symmetry

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22
Q

What type of parts does the nucleus have? (texture wise)

A

globular and fibrous

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23
Q

State the function of the nuclear envelope.

A

forms a selectively permeable barrier.

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24
Q

State the function of the nuclear lamina.

A

stabilises the nuclear envelope.

laminate= stabilize paper

25
Q

State the function of the lamins.

A

Lamins are associated with the chromatin.

26
Q

State the function of importin.

A
  • selective protein
  • aids in the transport/movement of substances across the nuclear membrane
27
Q

State the function of the nuclear pores.

A
  • allow to movement across and into the nucleus
    1) ions and solutes transfer using simple diffusion,
    2) large macromolecules are regulated by nucleoporins
28
Q

What does the large number of nuclear pores aid in?

A

simultaneous movement into and out of the cell.

29
Q

What are large macromolecules regulated by in the nucleus?

A

by nucleoporins

30
Q

State the function of chromatin.

A

allows for DNA replication, transcription, repair, cell division and genetic recombination.

31
Q

How is chromatin formed?

A

DNA and proteins

32
Q

What does chromatin change into?

A

chromosomes

33
Q

What does basophilic mean?

A

easily stained

34
Q

What moves into the nucleus?

A
  • enzymes
  • ribosomal proteins,
  • chromatin
  • transcription factors
35
Q

What moves out of the nucleus?

A
  • pre-mRNA
  • ribosomal subunits
  • RNA associated with proteins
36
Q

What is the nucleoplasm? What is its function?

A

A gel-like matrix in which nuclear components are suspended. It functions to cushion and protect the insides of the nucleus, provides a mode of transportation for enzymes and aids to maintain the cells shape.

37
Q

What is chromatin?

A
  • complex of DNA and proteins
  • forms chromosomes
38
Q

What are the two types of chromatin?

A

1) Euchromatin: transcribable, active, less condensed.
2) Heterochromatin: not transcribable, highly condensed

39
Q

What is the function of histone proteins?

A

help organise DNA.
- supercoil DNA
- allow for gene regulation (regulatory proteins)
- regulate transcription

40
Q

How is DNA coiled?

A

8 histone proteins and 1 DNA strand wrapped around 1.75 times.

41
Q

What is a nucleosome?

A

8 histone proteins (2H2A, 2H2B, 2H3, 2H4),
1.75 wrapped DNA strand.

42
Q

What is a chromatosome?

A

8 histone proteins (2H2A, 2H2B, 2H3, 2H4),
1.75x wrapped around DNA strand,
Additional H1 histone protein

43
Q

What does the H1 histone protein allow for?

A

higher order folding
(due to the ‘tail’ domains which cause interactions between nucleosomes and additional proteins)

44
Q

What do multiple nucleosomes form?

A

nucleosome array

45
Q

What do multiple chromatosomes form?

A

chromatin –> chromosome

46
Q

What are the two forms in which nucleosome arrays exist? Which one is more folded?

A

Solenoid and zigzag. Zigzag is folded more deeply.

47
Q

What is the interaction pattern in the solenoid form of nucleosome arrays?
What type of pattern (model) is the solenoid form?

A

interactions between histones occur sequentially (1,2,3,4 and so on)
The solenoid form is a “one start model”

48
Q

What is the interaction pattern in the zigzag form of nucleosome arrays?
What type of pattern (model) is the solenoid form?

A

DNA connects two opposing nucleosomes
(1 and 3, 2 and 4, and so on)
The zigzag pattern is differently known as the “two start model”

49
Q

When are chromosomes most compact?

A

during metaphase

50
Q

What are the components of a chromosome?

A
  • chromatid
  • centromere
  • chromatin
  • pellicle
  • matrix
  • telomere
  • chromonemata
  • satellite
  • primary constriction
  • secondary constriction
51
Q

What is the chromosome structure?

A

The chromosome is a supercoiled structure of chromatin.

52
Q

What are the 4 shapes of chromosomes?

A

Metacentric (V shaped)
Submetacentric (L shaped)
Acrocentric (J shaped)
Telocentric (rod shaped)

53
Q

State an example of a non typical chromosome.

A

Polytene chromosomes
Lampbrush chromosomes
Gender chromosomes

54
Q

How are polytene chromosomes formed?

A

the products of multiple rounds of S-phase remain tightly associated to form one supersized chromosome.

55
Q

What are polytene chromosomes? Which subset are they located in?

A

Polytene chromosomes are formed due to multiple products of S phase being tightly associated together.
they are part of the ENDOPOLYPLOID CELLS.

56
Q

What is part of the endopolyploid cells?

A

polytene chromosomes

57
Q

Explain the lampbrush chromosomes.

A
  • present in oocytes of birds, lower Vertebrata and invertebrates
  • form due to an active transcription of many genes
  • during meiosis prophase 1
58
Q

Explain how gender chromosomes are exceptions.

A
  • sex chromosomes determine the gender of an organism
  • XX is woman
  • XY is male
  • X is much bigger than Y

Cell Biology (12 decks)

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