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Biology > The developing Cell > Flashcards

The developing Cell Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Cell cycle

A

Cell growth, maturity and division
This is the process that all somatic cells in multicellular organisms use to grow and divide

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2
Q

Cell cycle 3 stages

A

interphase, mitosis, cytokenesis

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3
Q

Interphase

A

not part of mitosis

Growth 1- Cells grow in size & mass, organelles replicated, inc protein synthesis *(chloroplasts & mitochondria not replicated)

Synthesis- DNA replication using SCR

Growth 2- energy stores increase, cell continues to increase in size & mass, chloroplasts & mitochondria increase in size and divide

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4
Q

What does G1 checkpoint check for

A

-Chemicals needed for replication present
-Damage in DNA before synthesis
-Suitable in size
-Sufficient nutrients

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5
Q

What does G2 checkpoint check for

A

-All DNA has replicated without damage
-Cell is of correct size

Otherwise, daughter cells will not receive identical genetic information

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6
Q

Mitosis

A

Nuclear division- produces 2 genetically identical nuclei

Are them distributed unto two genetically identical daughter cells

I push miss around the corner

prophase, metaphase, anaphase, telophase

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7
Q

Prophase

(preparing)

A

-Chromosome condense (can now be seen easier)
-Each chromosome consists of 2 sister chromatids joined by a centromere
-Centrioles move towards poles
-Spindle fibres form
-Nucleolus & nuclear envelope breaks down

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8
Q

Metaphase

(middle)

A

-Chromosomes line up against the equator
-Spindle fibres attach to centromere

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9
Q

Anaphase

(pulled Apart. Arrow heads)

A

-Spindle fibres contract
-Centromere splits
-Daughter chromosomes pulled to opposite poles, centromere first

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10
Q

Telophase
(Two)

A

-Daughter chromosomes reach poles
-Chromosomes uncoil & lengthen
-Spindle fibres disintegrate
-Nuclear envelope & nucleolus reforms

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11
Q

Summary of mitosis

A

Animal Plant
most tissue. meristematic only
cell becomes round no change
Centrioles No
Spindles disappear Remain
Microfilaments No

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12
Q

Some cells lose ability to divide

A

eg. neurones, muscle cells

They leave the cycle temporarily or permanently due to:

a) Differentiation
b)Damaged DNA. Cell no longer viable so enter G0.

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13
Q

Importance of mitosis

A

-Growth of multicellular organisms
-repir damaged tissues
-replacement of cells
-asexual reproduction

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14
Q

Homologous chromosomes

A

46 (23 pairs)
Each pair is made up of one maternal and one paternal

Same: sequence of genes, same length, position of centromere
Different: Origins, alleles

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15
Q

how do we analyse the cell cycle?

A

flow cytometry:
- DNA stained with fluorescent dye
- passed through flow cytometer
- fluorescent intensity recorded

more DNA = more fluorescence ∴ increases G1 -> S -> G2

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16
Q

Cells which do not carry out mitosis

A

Mature RBC, neurones

17
Q

Cell cycle control

A

Sequence & timing controlled by cyclins (protein)

which activate enzymes called cyclin-dependent kinases

which catalyse the addition of a phosphate group onto a protein, changing its tertiary structure

Specific CDKS control specific steps in cel cycle

18
Q

What happens if errors are detected during cell cycle

A

p21 binds to CDKs
idea of complementary, blocks active site
This halts cell cycle at G1 stage in interphase

without p21, cancer. It is a tumour suppressor gene

Mutations to cyclin genes or CDKs can lead to failure to repair DNA-> cancer

19
Q

Cytokenesis

A

Process of cytoplasm and two nuclei being divided to physically form 2 new daughter cells

20
Q

Cytokenesis in animal cells

A

-CSM invaginates
-Cleaveage furrow forms in middle of cell
-csm pinches until 2 sides meet
-Cytoplasm & organelles are divided equally into 2 new daughter cells

21
Q

Cytokenesis in plant cells

A

-Only in meristematic tissue
-vesicles from Golgi assemble on the equator= cell plate
-vesicles fuse with one another and the csm
-Cell wall forms along middle lamella
-Cytoplasm & organelles are divided equally into 2 new daughter cells
-Plant cells are inelastic due to cellulose cell wall

22
Q

Synoptic link with cell cycle and cancer

A

-Negative regulator molecules (p53, p21) act primarily in G1 checkpoint and prevent cell from moving forward to synthesis until DNA is repaired

-p53 halts the cell cycle and recruits enzymes to repair DNA. If it cannot be repaired, apoptosis is initiated

23
Q

Apoptosis

A

-Programmed cell death
(ordered and controlled process)

24
Q

Necrosis

A

-unregulated cell death after trauma
-surface membrane ruptures, release of hydrolytic enzymes

25
Q

Control of apoptosis

A

Cell signals are received from inside & outside of cells
-signals: p53, cytokines, hormones, growth factors etc
-Different signals induce apoptosis in different tissues

26
Q

Apoptosis

A

-cell shrinks & chromatin in nucleus condenses (pyknosis)
-CSM breaks down & blebs form
-DNA breaks down
-Cell organelles break down
-Cell fragments into apoptotic bodies
-Macrophages engulf cell fragments

27
Q

Uses of apoptosis

A

-fetal eg. toes
-puberty
-immune system (destruction of harmful immune cells)
-Formation of connections between neurones in brain

28
Q

Stimuli

A

internal: eg. DNA change. Damage detected by cyclins, hals cell cycle -> apoptosis

external: attack by a pathogen

29
Q

Detecting apoptosis & necrosis

A

-Flow cytometry
-Annexin V is used to detect apoptotic cells
-Binds to phosphatidylserine, a marker of apoptosis when in monolayer

nectrotic late apoptotic
Live ealy apoptotic

30
Q

Stem cells

A

Unspecialised
Are potent
Can differentiate into specialised cells

31
Q

Cell specialisation

A

At day 19, cells differentiate, producing specialised cells
Genes are switched on/off
Cells divide by mitosis to produce genetically identical clones
Groups of cells form tissues
Groups of tissues form Organs

32
Q

Properties of stem cells

A

self-renewal: ability to divide many times while maintaining an unspecialised state

potency: ability to differentiate into specialised cells

33
Q

Totipotent cells

(The prime minister)

A

Can form all cells in the body plus placental cells

Source: very early embryos, meristematic tissue

34
Q

Pluripotent cells

A

Can form all cells in body but not placental cells

source: inner cell mass of blastocyst

eg use: cell replacement therapies- produce pancreatic cells to treat diabetes

35
Q

Mutipotent cells

A

Adult stem cells can give rise to a limited number of cell types.

source: bone marrow, bone, umbilical chord

eg. uses: treat leukaemia, blood cancers, bone cancers

36
Q

Problems with stem cells therapies

A

-Embryo rights, destruction of human embryos, hasn’t produced any viable long term treatments
-Better to turn differentiated cells back into pluripotent

37
Q

Process of stem cell differentiation

A

-stem Cells undergoes mitosis
-Genes are switched on/off
-New proteins made
-cell becomes specialised

Biology (18 decks)

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