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Alevel Biology year 1 > Cell division, Cell diversity and Cellular organisation > Flashcards

Cell division, Cell diversity and Cellular organisation Flashcards

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1
Q

3 phases of cell cycle

A

interphase, mitotic phase, G0 phase

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2
Q

interphase

A

time of growth and preparation for cellular division
DNA replicated and checked for errors
protein synthesis in cytoplasm
chloroplast and mitochondria grow in number

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3
Q

stages of interphase

A

g1- growth phase(organelles produced and replicate
S- DNA replication
g2- second growth phase continued growth in size and DNA checked for error

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3
Q

miotic phase

A

mitosis- nucleus divides
cytokinesis - cytoplasm divides

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3
Q

G0

A

cell leaves cycle temporarily or permamently
differentiation- cell specialised to carry out a function can no longer divide
DNA might be damaged so it enters arrrest apoptosis

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3
Q

how do chromosomes act in mitosis

A

DNA molecules converted into two identical DNA molecules called chromatid joined together by the centromere
important to be kept together to be precisely manoeuvred/ segregated

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4
Q

what is the importance of mitosis

A

ensures both daughter cells are genetically identical to the parent cells, they will have the exact copy of DNA in present cells and the same number of chromosomes
growth, repair, asexual reproduction

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4
Q

how is the cell cycle controlled

A

checkpoints are done to ensure the cell is process of each phase has been accurately completed
G1check point- end of g1 phase makes sure cell has met requirements
G2check point- at the end of the G2 phase(checks DNA has been replicated properly and cell begins mitosis
spindle checkpoint- makes sure all of the chromosomes are correctly attached to the spindles

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4
Q

what are the stages of mitosis

A

prophase, metaphase, anaphase and telophase
they are all interlinked and work between themselves

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4
Q

Prophase

A

chromatin condenses and becomes visible and nuclear membrane breaks down
microtubules form spindle shaped structures linking poles of the cell
centrioles migrate to the poles of cell to help the formation of the spindle fibres
the spindle fibres attach to parts of the chromosomes and move to metaphase plate
at the end nuclear envelope has disappeared

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4
Q

metaphase

A

chromosomes moved by the spindle fibres to the metaphase plate and lined upheld in position

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4
Q

Anaphase

A

The spindle fibres attach to the centromeres of the chromosome on both sides and splits it in two, fibres contract and pull the chromatids to each side of the cell

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5
Q

telophase

A

Once the chromatids reach the poles they are called chromosomes, new sets of chromosomes assemble at the poles and the nuclear envelope forms around them, chromosomes uncoil and nucleolus forms

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6
Q

cytokinesis

A

actual splitting of the membrane into two different cells

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7
Q

animal cytokinesis

A

cleavage furrow forms around middle of the cell membrane pulled inwards until it can fuse with itself and pinch of into two

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8
Q

plant cell cytokinesis

A

cell wall stops cleavage furrow, so vesicles from the Golgi apparatus assemble at the metaphase plant all using together until the cell is split into two and new cell walls form around the membranes

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9
Q

what type of chromosomes are made in mitosis

A

diploid

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10
Q

what type of chromosomes are made in meosis

A

haploid

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11
Q

what are homolgus chromosomes

A

chromosomes from each parent that have the same matching genes(pair) for each characteristic)
same genes in the same posititns

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12
Q

Allele?

A

different versions of the same gene eg the gene for eye colour varies blue/ brown eyes

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13
Q

what are the stages of meiosis

A

meiosis 1- reduction division when the pairs of chromosomes are separated in two cells
meiosis 2- second division pair of chromosomes are separated forming 2 more cells 4 haploid daughter cells in total

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14
Q

Meiosis 1(p1)

A

-chromosomes condense nuclear envelope/ nucleolus disappears
-spindle fibres begin to form
-homologous chromosomes pair up (bivalents)
-chromosomes are large molecules and as they move around in cytoplasm they get entangled and DNA crosses over

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15
Q

Meiosis1(m1)

A

homologous pairs of chromosomes assemble on the metaphase plate
assembly of the homologous chromosomes on the metaphase plate is random maternal/ paternal chromosomes can end up facing either pole(independent assortment)

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16
Q

Meiosis1(anaphase 1)

A

homologous chromosomes pulled apart but the chromatid stay together

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17
Q

crossing over

A

When entangled chromatids are pulled apart they break off and exchange DNA points at which they break/join (chiasmata)
when re-joined they form recombinant chromosomes
genes shared (different alleles for genetic variation

18
Q

meiosis1(T1)

A

same as mitosis
chromosomes assemble they uncoil membrane reforms and cytokinesis divides the two cells
haploid cells

19
Q

meiosis2(p2)

A

chromosomes consist of 2 chromatid condense and become visible
nuclear envelope breaks down
spindle fibres form

20
Q

meiosis2(m2)

A

individual chromosomes line up at metaphase plate
chromatids aren’t identical so there is independent assortment and more genetic variation

21
Q

meiosis2(a2)

A

chromatids of individual chromosomes pulled to opposite poles after centromere division

22
Q

meiosis2(t2)

A

assemble at the poles uncoil into chromatin nuclear envelope and nucleolus appear
cytokinesis causes the cells to be 4 daughter haploid cells which are genetically varied

23
Q

levels of organism?

A

specialised cells- tissues-organs-organ systems- whole organism

24
Q

Specialised cells

A

differentiated, meaning they are specialised for their function

25
Q

erythrocytes specialisations

A

flattened biconcave for large SA:VOL ratio for o2 transport
have no nucleus more space for haemoglobin
flexible to squeeze through capillaries

26
Q

neutrophils(wbc) specialisations

A

multi loved nucleus to squeeze though small gaps for infections
granular cytoplasm with many lysosomes that contain enzymes to attack pathogens

27
Q

Sperm cells specialisations

A

deliver genetic information
tail/flagellum to move
plentiful mitochondria to supply the energy needed to swim
acrosome that contain digestive enzymes to penetrate the egg

28
Q

Palisade cells

A

Large amounts of chloroplasts for light absorption. Thin cell walls which increases rate of diffusion for Co2 ,choloroplast can move in the cytoplasm

29
Q

root hair cells

A

Large surface rea for maximum water uptake from the soil

30
Q

Guard cells

A

form opening of stomata, change shape to prevent water loss. cell wall thicker on one side shape symmetrically as the volume changes

31
Q

categories of tissues

A

nervous tissue; adapted to support transmission of electrical impulses
epithelial tissue; adapted to cover body surfaces (internal/external)
muscle tissue; adapted to contract
connective tissue; to hold other tissues together or a transport medium

32
Q

squamous epithelium

A

flat cells and thin(one cell thick)
for fast diffusion of gaseous material
in lung lining for rapid diffusion of o2 into the blood

33
Q

ciliated epithelium

A

line with cilia that beat to move mucus/ trapped particles out of trachea
they have goblet cells that secrete mucus to trap any pathogens

34
Q

cartilage

A

connective tissue contains fibres of elastin and collagen.
firm tissue that prevents ends of bones from rubbing together

35
Q

muscle

A

can shorten and contract which moves the body
skeletal muscles fibres( attached to bone)
contains myofibrils and contractile proteins

36
Q

epidermis

A

closely pack cells on plant surface which is covered by a waxy cuticle to reduce water loss
stomata are present in the epidermis

37
Q

xylem tissue

A

transport of water/ minerals throughout plants
composed of vessel elements which are elongated dead cells
strengthened by lining water proof and provides strength

38
Q

phloem tissue

A

transports of assimilates(sucrose mainly)
from leaves to where it is needed, column of sieve tube elements separated by sieve plates

39
Q

organ systems

A

digestive system, cardiovascular system, gaseous exchange system

40
Q

what is a stem cell

A

an undifferentiated cell that can differentiate into any cell, can keep dividing and be a source for cells necessary for growth, development and repair. Once specialised they can no longer divide
too slow division leads to aging to fast division leads to cancer

41
Q

what is stem cell potency

A

ability for a cell to differentiate (potency)

42
Q

totipotent-

A

can differentiate into any type of cell, fertilised egg, zygote are totipotent cells meaning they can produce a whole organism

43
Q

pluripotent

A

can form all tissue but not whole organisms, mainly in early embryos origin of different tissues in a cell

44
Q

multipotent

A

wide range of cells within a certain tissue(haemopoietic can give rise to different types of blood types in the bone marrow )

45
Q

differentiation

A

when cells change shape for certain functions or a specific roles
all RBC come from stem cells in the bone marrow

46
Q

replacement of red and white blood cells

A

they lack organelles and have a short life span(120) need to be replaced constantly
stem cell colonies produce 3 billion erythrocytes per kg of body mass every day
neutrophils live about 6 hours so stem cell colonies in bone marrow produce about 1.6 billion per kg per hour of WBC which increases during infection

47
Q

what are the sources of stem cells

A

embryonic stem cells- early stage of development they are totipotent, after 7 days they become blastocyst and the cells are now pluripotent
adult stem cells- throughout a persons life time, found in bone marrow they are multipotent but can be triggered to become pluripotent

48
Q

whys are embryonic cells preferred

A

plenty umbilical cords to use and there is no need for an invade process to remove the stem cells

49
Q

what is the source of stems cells in plants

A

meristematic tissue which is found where growth occurs in plants(root/shoot)
also found between the phloem and xylem (vascular cambium) which differentiate into xylem or phloem cells

50
Q

Use of stem cells

A
51
Q

heart disease

A

muscle tissue damaged from heat attack

52
Q

embryo creation

A

embryos created intentionally to take the cells away from them and kill the cells controversy as to if the cell has rights or not

53
Q
A

Alevel Biology year 1 (14 decks)

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