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Biology > Cell Division > Flashcards

Cell Division Flashcards

1
Q

Specialised cells

A

Cells are differentiated specialised to carry out specific functions

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2
Q

Erythrocytes

A

RBCs - flattened biconcave shape increase sa to vol ratio essential for O2 transport
No organelles space for haemoglobin
Flexible to squeeze through capillaries

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3
Q

Neutrophils

A

A type of wbc
Multi loved nucleus making it easier to squeeze through small gaps to get to infections
Cytoplasm= many lysosomes that contain enzymes to attack pathogens

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4
Q

Sperm cells

A

Tail capable of moving to egg
Many mitochondria for energy to swim
Acrosome(head) contains digestive enzymes to penetrate egg

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5
Q

Palisade cells

A

In mesophyll later
Contain chloroplast to absorb large amounts of light
Rectangular to closely pack
Thin walls diffusion of CO2 easy
Large vacuole to maintain turbot pressure
Chloroplasts can move

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6
Q

Root hair cells

A

Large sa to vol ratio maximising uptake of water and mineral from soil

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7
Q

Guard cells

A

Form stomata
Guard cells lose water - change shape stomata closes
Cell wall thicker on one side so doesn’t change shape symmetrically

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8
Q

Tissue catergories

A

Nervous
Epithelial
Muscle
Connective

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9
Q

Squamous epithelium

A

Very thin and flat 1 cell thick
forms lining of the lungs
Present when rapid diffusion across surface is essential

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10
Q

Ciliates epithelial cells

A

Cilia on surface move in rhythmic manner to sweep mucus from lungs
Goblet cells present to release mucus to trap unwanted shit reaching the alveoli

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11
Q

Cartilage

A

Connective tissue
Fibres of elastin and collagen
Chondrocyte cells embedded in extra cellular matrix
Prevents ends of bones from rubbing

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12
Q

Tissues in plants

A

Epidermis
Vascular

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13
Q

Epidermis

A

Single layer of closely packed cells covering surfaces of plants
Covered by waxy cuticle layer to reduce water loss
Stomata present to allow CO2 in and out and oxygen and water out

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14
Q

Xylem and phloem tissue

A

Vascular tissues found in stems of plants to transport needed materials

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15
Q

Stem cells

A

Undifferentiated cells
Able to undergo continuous cell division
Source of new growth development and tissue repair
When specialised lose ability to divide

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16
Q

Potency

A

A stem cells ability to differentiate into different cells

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17
Q

Totipotent

A

Can differentiate into any type of cell
Fertilised egg or zygote and 8/16 cells from first mitotic devisions
Destined to produce a whole organism

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18
Q

Pluripotent

A

Stem cells can form all tissue types but not whole organisms
Present in early embryos
Origin of different types of tissue within organism

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19
Q

Multi potent

A

Stem cells that can only form a range of cells within certain tissue type
Eg haematopoetic stem cells in bone marrow are multi because differentiate to various types of blood cells

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20
Q

Replacement of blood cells

A

RBCs every 120 days stem cells in bone marrow produce 3 bill per kg of body mass per day
WBCs live for 6 hours and produced at 1.6 billion per kg per hour increasing during infection

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21
Q

Sources of animal stem cells

A

Embryonic stem cells- totipotent stem cells 7 days later blastocyst forms pluripotent cells
Adult stem cells- bone no arrow multi potent also in umbilical cords - invasive surgery not needed and stored just in case needs in future (no rejection)

22
Q

Sources of plant stem cells

A

Meristematic tissues
Tips of roots and shoots (apical meristems)
Located between xylem and phloem called cambium - differentiate into vascular tissue
Constant pluripotent

23
Q

Uses of stem cells

A

Heart disease - replace muscle tissue
Type 1 diabetes- stem cells form beta cells
Parkinson’s - form dopamine producing cells in brain
Alzheimer’s - differentiate form new brain cells
Macular degeneration- stem cells in blindness
Birth defects- reverse untreatable birth defects
Spinal injuries - rats spines rebuilt using stem cells
Treating burns
Drug trials

24
Q

Ethics

A

Embryonic stem cells in therapies
Destruction of embryo to extract stem cells - this is murder and religious objections embryo has rights etc

25
Q

Cell cycle

A

Interphase
Mitotic phase

26
Q

Interphase

A

Long periods of growth and normal working separate divisions
- Dna is replicated and check
-Protein synthesis occurs in cytoplasm
- mitochondria and chloroplast grow and divide
- normal metabolic processes

27
Q

Interphase stages

A

G1- proteins from organelles are synthesised and produced - replicate
S- synthesis dna is replicated in the nucleus
G2- duplicated dna checked for errors and cell increase in size and energy stores increased

28
Q

Mitosis

A

Cell division
Mitosis - nucleus divides
Cutokinesis- cytoplasm divides and 2 cells are produced

29
Q

G0

A

Phase when the cell leaves the cycle
- differentiation = cell specialised no longer able to divide
- dna may be damaged no longer viable all cells eventually become senescent (deteriorate)
-No of these cells increase w age- cancer
Only few can return to cycle eg lymphocytes

30
Q

Controlling cell cycle

A

Ensure cell only divides when grown to right size
Checkpoints control mechanisms control and verify before progressing
G1 check - if correct trigger dna rep
G2 check - dna check cell initiates mitosis
Metaphase checkpoint - mitosis when all spindles attach to chromo in lines

31
Q

Chromatids

A

All dna in nucleus replicated in interphase each chromosomes converted into 2 dna molecules - chromatids

32
Q

Centromeres

A

Chromosomes joined together at a region called centromeres
To keep chromo together during mitosis so precisely manoeuvred and equally split into 2 daughter cells

33
Q

Stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

34
Q

Prophase

A

Chromatin fibres(proteins dna and rna) coil and condense to form chromosomes
Nucleolus and nucleus membrane disappear
Microtubules make spindles linking poles of cell
Centrioles opposite ends help form spindles- attach to centromeres and move chromosome to the middle

35
Q

Metaphase

A

Chromosomes are moved to form a plane in the centre of the cell all in line forming metaphase plate and held in position

36
Q

Anaphase

A

Centromeres divide and chromatids are separated by shortening spindle fibres
V shape drag by centromeres through cytosol

37
Q

Telophase

A

Chromatids reach poles and are called chromosomes
2 new sets of chromo and nuclear envelope reforms

38
Q

Cytokinesis

A

Starts during telophase
Actual splitting into 2 separate cells
Animal = cytoskeleton pulls membrane inwards until close enough to fuse
Plant = vesicles from Golgi assemble in middle and fuse with each other and the cell surface membrane dividing into 2 wall forms here

39
Q

Meiosis

A

Process in which gametes are formed
Produce 4 daughter cells
Occur in diploid cells
Fuse mother and father gametes so half no of chromosomes required

40
Q

Stages of meiosis

A

Meiosis 1 - first div pairs of chromosomes separated into 2 cells each containing 1 full set instead of two
Meiosis 2 - pairs of chromatids spectated forming 2 more cells

41
Q

Prophase 1

A

Homologous chromosomes link together forming chiasmata (bivalents )
1x maternal pair 1x paternal pair
crossing over takes place exchanging certain alleles

42
Q

Metaphase 1

A

Homologous pairs aligned on metaphase plate
Orientation of each homologous pair is random cannot predict whether the paternal or maternal chromosome will end up in what gamete - independent assortment

43
Q

Anaphase 1

A

Chromosomes are pulled to opposit poles
Sections of crossovers break off and join (chiasmata) resulting in exchange of DNA
Forms recombinant chromatids - combo different to original chromatids
Forms genetic variation

44
Q

Telophase 1

A

Chromosomes assemble at each pole and nuclear membrane reforms
Cytokinesis occurs
Diploid to haploid is complete

45
Q

Prophase 2

A

Chromosomes condense and become visible
Spindle formation begins

46
Q

Metaphase 2

A

Individual chromosomes assemble on metaphase plate
Due to crossing over chromatids are no longer identical independent assortment

47
Q

Anaphase 2

A

Chromatids of Individual chromosomes pulled to opposite poles after division of centromeres

48
Q

Telophase 2

A

Chromatids assemble at poles
Nuclear envelope reforms
Cytokinesis forms 4 daughter cells genetically different due to crossing over and independent assortment

49
Q

Chiasmata

A

Homologous pairs link together to form this
Breaks in anaphase 1 exchanging alleles

50
Q

Independent assortment

A

Orientation of homologous chromosomes are random and cannot predict what chromosome will end up in the gamete whether it be maternal or paternal
result in many different combos of alleles facing the poles

51
Q

How does sexual reproduction lead to genetic variation

A

Variety of alleles inherited more than one parent
Random fertilisation
Meiosis produces genetically different gametes
Crossing over in prophase 1
Independent assortment in meta 1

Biology (24 decks)

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