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biology > Cell Division, Cell Diversity and Cellular Organisation > Flashcards

Cell Division, Cell Diversity and Cellular Organisation Flashcards

1
Q

Specialisation of Erythrocytes (red blood cells)

A

Flattened biconcave shape: Increases SA:V

No nuclei: Space for haemoglobin

Flexible: So they can squeeze through narrow capilaries

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2
Q

Specialisation of Neutrophil

A

Multilobed nucleus: Can squeeze through small gaps to reach the site of infection

Many Lysosome containing enzymes which digest and destroy pathogens

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2
Q

Specialisation of sperm cells

A

Flagellum: Movement to the egg

Mitochondria: Energy for the movement

Acrosome: containing enzymes so sperm penetrates egg

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3
Q

Specialisation of Squamous Epithelial cells

A

Flattened Shape: Short diffusion distance

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4
Q

Role of epithelial cells

A

Protect body surfaces + aids diffusion and absorption

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5
Q

Role and specialisation of ciliated epithelial cells

A

Role: Moves substances across the respiratory system + female reproductive system.

Cillia: Moves mucus and eggs to the site of fertilisation

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6
Q

Root cell function and specialisation

A

Specialised for water and mineral ion absorption.

Vacuole containing cell sap: Maintains concentration gradient

Root hair: Increase absorption surface area

Thin cellulose wall: Short diffusion distance

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7
Q

Palisade cell function and specialisation

A

Large number of chloroplasts: Absorbs light for photosynthesis

Thin cell walls: Increase rate of carbon dioxide diffusion

Large vacuole: turgidity

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8
Q

Guard cells specialisation and function.

A

Controls the opening of the stomata

Thick inner walls and thin outer walls: Allows the cell to bend when their turgid.

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9
Q

Xylem structure

A

Elongated dead cells strengthened by lignin

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10
Q

Phloem

A

Sieve tube separated by sieve plates

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11
Q

What term describes cells which are adapted to a specialised function?

A

differentiated cells

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12
Q

What are stem cells?

A

Undifferentiated cells

When they undergo mitosis, they either form new stem cells or differentiate into specialised cells.

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13
Q

What are the three types of potency

A

Totipotent
Pluripotent
Multipotent

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14
Q

Totipotent

A

Any cell

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15
Q

Pluripotent

A

Most cells

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16
Q

Multipotent

A

Limited number of cells

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17
Q

Where are multipotent stem cells found?

A

Bone marrow

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18
Q

What can bone marrow stem cells differentiate into?

A

Erythrocyte and Neutrophils

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19
Q

Where are totipotent stem cells found?

A

In embryos

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20
Q

Where are stem cells found in plants?

A

Meristem

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21
Q

Where is meristem found in a stem cell?

A

Shoots
Root
Between xylem and phloem

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22
Q

How are stem cells used in medicine?

A

Stem cells are reintroduced into damaged tissue and can self replicate

There they replace destroyed tissue and this is useful for treating illnesses like Parkinson’s and alzheimer’s

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23
Q

How are stem cells used in research?

A

Drugs are tested on stem cells rather than people these tests can indicate how effective the drug is and whether there are side effects.

24
Issues with using stem cells
Taken from embryos, which destroys the embryo Also harvesting stem cells from bone marrow is painful and risky There is a risk of infection and also that the patient's immune system will reject the donated cells.
25
Evaluate the use of stem cells in treating disease. [6 marks]
**Concerns** Conflicting legal and ethical standards / Current embryonic stem cell harvesting requires the death of an embryo Possibility for cells to be rejected; Obtaining the cell culture can be challenging; costly process **Benefits** Stem cells have regenerative properties Using stem cells means more can be learned about the process of development for other diseases New established protocols ensure safety of embryo and others throughout process; The procedure to plant them is relatively non-invasive.
26
What happens in G1 Phase
organelles replicated synthesises proteins and enzymes cell size increase
27
What happens in the S phase
DNA replication
28
What happens in the G2 phase
Cell growth, cytoplasm increase
29
Prophase
Chromatin- DNA + Histone proteins Chromatin condensed into chromosomes. Nuclear envelope breaks down. Nucleolus disappears Spindle fibres form
30
Metaphase
Chromatids separate Chromosomes moves to the centre of the cell by spindles
31
Anaphase
Spindle fibres contract Chromatids move to opposite poles of the cells by spindle fibres attached to centrosomes
32
Telophase
Nuclear envelope reforms around each chromatid Cytoplasm divides by cytokinesis Produces two identical daughter cells
33
Cytokinesis
Animal cell: Cleavage burrow forms Plant cell: Vesicles assemble at metaphase plate. Vesicles fuse and fuse with membrane forming two cells
34
G0 phase
Cell leaves cell cycle Either because it has damaged DNA Or because it is a differentiated cell that is no longer able to divide
35
What happens to telomeres as we age
They shorten and shorten and sometimes it causes the cells to go in an irreversible state where they can't re enter the cell cycle
36
Purposes of mitosis
Asexual reproduction Growth Repair
37
Where does meiosis take place
Sex organs Only used to produce gametes
38
Why is important that gametes are haploids?
During fertilisation the gametes fuse together to produced a fertilised egg or zygote.
39
What is a bivalent?
Two chromosomes in a homologous pair that come together.
40
What are chiasmata?
Points where the chromatids are joined.
41
What are recombinant chromosomes?
Parts of chromatids breaking off and exchanging between homologous chromosomes. Exchanging DNA
42
Meiosis 1
Homologous chromosomes are separated from each other.
43
Meiosis 2
Sister chromatids are separated from each other
44
Prophase 1 Cool Cats Nap Constantly & Stretch
Chromosomes condense and become visible Crossing over takes place- alleles are exchanged between the homologous chromosomes. Nuclear membrane breaks down Centrioles move to opposite poles of the cell. Spindle fibres also start to assemble
45
Metaphase 1
Pairs of homologous chromosomes are lined up on the equator of the spindle apparatus
46
Anaphase 1
Spindle fibres shorten and the homologous chromosomes move towards opposite poles. Chiasmata also breaks.
47
Telophase 1 Cool New Cells Created
Chromosomes reach the poles of the cell Nuclear membranes reform, chromosomes uncoil back to chromatin state Cell undergoes cytokinesis dividing into two haploid cells as they don't contain pairs of homologous chromosomes. Cool → Chromosomes reach poles New → Nuclear membrane reforms Cells → Chromosomes uncoil Created → Cytokinesis occurs
48
meiosis 1 jingle
🎶 **"Meiosis I, let’s break it down, Cells divide, but don’t back down! Prophase I – Chromosomes show, Crossing over steals the show! Metaphase I – They line up tight, Homologues paired, left and right! Anaphase I – Pulled away, To opposite poles, no delay! Telophase I – Almost done, Two haploid cells, cytokinesis won!"** 🎶
49
Why do the cells become haploid after cytokinesis?
They no longer contain pairs of homologous chromosomes
50
Prophase 2
Chromosomes condense and become visible again Nuclear membrane breaks down Spindle fibres develop
51
Metaphase 2
Chromosomes line up on equator of spindle apparatus
52
Anaphase 2
Centromere of the chromosome divides Spindle fibres shorten Chromatids are pulled to opposite sides of the cell
53
Telophase 2
Chromatids reach poles of the cells and are now chromosomes Nuclear membranes reform and the chromosomes uncoil back to chromatin state
54
Cytokinesis
Each cell undergoes cytokinesis to produce two haploid cells
55
Why is meiosis reduction division?
Chromosome number halves
56
number of genetically different gametes produced by independent assortment.
2 n (n= number of homologous chromosome pairs)
57
what is independent assortment and why is it important?
It refers to how homologous chromosome pairs line up randomly along the equator of the cell before being separated It creates genetic variation because different combinations of maternal and paternal chromosomes end up in the gametes. Independent Assortment = Infinite Arrangements!

biology (8 decks)

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