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biology > cell division, cell diversity & cell differentiation > Flashcards

cell division, cell diversity & cell differentiation Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

how do cells divide in eukaryotic cells?

A

they enter the cell cycle and divide by either mitosis or meiosis

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2
Q

how do cells divide in prokaryotic cells?

A

binary fission

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3
Q

what are the 3 stages of the cell cycle?

A

interphase (G1, S, G2) , nuclear division (mitosis or meiosis), & cytokinesis

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4
Q

what happens at G1?

A
  • protein synthesis occurs to make proteins involved in synthesising organelles
  • the organelles replicate
  • cell is checked that it is the correct size, has the correct nutrients, growth factors, and that there are no mutations, if the cell doesn’t pass these checks replication will not continue
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5
Q

what happens at S phase?

A

DNA is replicated

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6
Q

what happens at G2?

A

the cell continues to grow, energy stores increase, and the newly replicated DNA is checked for any copying errors

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7
Q

what is mitosis?

A

the creation of 2 identical diploid cells

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8
Q

what is mitosis used for?

A
  • growth
  • tissue repair
  • asexual reproduction in plants, animals & fungi
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9
Q

what are the 4 key stages of mitosis?

A

prophase, metaphase, anaphase & telophase

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10
Q

what happens at prophase?

A

the chromosomes condense and become visisble

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11
Q

what do the centrioles do during prophase?

A

they separate and move to opposite poles of the cell, they create spindle fibres which are released from both poles to create a spindle apparatus which attach to the centromere, and chromatids on the chromosome in late prophase

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12
Q

what happens during metaphase?

A

the chromosomes align along the equator of the cell - the spindle fibres are released from the centrioles and attach to the centromere & chromatids

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13
Q

what is the spindle assembly checkpoint & when does it occur?

A

it occurs during metaphase, it is a check to ensure every chromosome has attached to a spindle fibre before mitosis can proceed into anaphase

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14
Q

what happens during anaphase?

A

the spindle fibres start to shorten and move towards the centrioles and pull the centromere and chromatids they are bound to towards the opposite poles, this causes the centromere to divide into 2 and the individual chromatids are pulled to each opposite pole - this stage requires energy in the form of ATP which is provided by respiration in the mitochondria

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15
Q

what happens during telophase?

A

the chromosomes are now at each pole of the cell and become longer and thinner again, the spindle fibres diintergrate, and the nuclear membrane reform around the 2 chromosomes

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16
Q

what generally happens during cytokinesis?

A

the cytoplasm splits into 2 genetically identical cells

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17
Q

what happens during cytokinesis in animals?

A

a cleavage furrow forms in the middle of the cell, and the cytoskeleton causes the cell membrane to draw inwards until the cell splits into 2

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18
Q

what happens during cytokinesis in plants?

A

the cell membrane splits into 2 new cells due to the fusing of vesicles from the golgi apparatus, the cell wall forms new sections around the membrane to complete the division into 2 new cells

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19
Q

what is meiosis?

A

when there are 2 nuclear divisions which result in 4 genetically different haploid daughter cells

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20
Q

what are the stages in meiosis?

A

prophase 1, metaphase 1, anaphase 1, telophase 1, prophase 2, metaphase 2, anaphase 2, & telophase 2

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21
Q

what is a haploid cell?

A

when there is one copy of each chromosome

22
Q

what is a diploid cell?

A

when there are 2 copies of each chromosome

23
Q

what happens during prophase 1?

A
  • chromatin condenses and each chromosome supercoils
  • nuclear envelope breaks down, and spindle threads of tubulin protein form from the centriole in animal cells
  • the chromosomes come together in homologous pairs (each member of the pair consists of 2 chromatids)
  • crossing over occurs where non-sister chromatids wrap around each other and may swap sections so that the alleles are shuffled
24
Q

what happens in metaphase 1?

A
  • the pairs of homologous chromosomes, still in their crossed over state, attach along the equator of the spindle
  • each attaches to a spindle thread by its centromere
  • the homologous pairs are arranged randomly, with the members of each pair facing opposite poles of the cell, this arrangement is independent assortment
  • the way that they line up in metaphase determines how they will segregate independantly when pulled apart during anaphase
25
Q

what happens in anaphase 1?

A
  • the members of each pair of homologous chromosomes are pulled apart by motor proteins that drag them along the tubulin threads of the spindle
  • the centromeres do not divide, and each chromosome consists of 2 chromatids
  • the crossed-over areas separate from each-other, resulting in swapped areas of chromosome and allele shuffling
26
Q

what happens in telophase 1 in animal cells?

A
  • 2 new nuclear envelopes form around each set of chromosomes, and the cell divides by cytokinesis, there is then a short interphase when the chromosomes uncoil
  • each new nucleus contains half the original number of chromosomes, but each chromosome consists of 2 chromatids
27
Q

what happens in telophase 1 in plant cells

A

the cell goes straigh from anaphase 1 into prophase 2

28
Q

what happens in prophase 2?

A
  • if the nuclear envelopes have reformed, they then now break down
  • the chromosomes coil and condense, each one consisting of 2 chromatids
  • the chromatids of each chromosome are no longer identical, due to crossing over in prophase 1
  • spindles form
29
Q

what happens in metaphase 2?

A
  • the chromosomes attch, by their centromere, to the equator of the spindle
  • the chromatids of each chromosome are randomly arranged
  • the way that they are arranged will determine how the chromatids separate during anaphase
30
Q

what happens in anaphase 2?

A
  • the centromeres divide
  • the chromatids of each chromosome are pulled apart by motor proteins that drag them along the tubulin threads of the spindle, towards opposite poles
  • the chromatids are therefore randomly segregated
31
Q

what happens in telophase 2 in animals

A
  • nuclear envelopes form around each of the 4 haploid nuclei
  • the 2 cells now divide to give 4 haploid cells
32
Q

what happens in telophase 2 in plants?

A
  • nuclear envelopes form around each of the 4 haploid nuclei
  • a tetrad of 4 haploid cells is formed
33
Q

what is the order of organisation in multicellular organisms (smallest to largest)?

A

cells -> tissue -> organ -> organ system -> organism

34
Q

what is the structure & function of erythrocytes?

A
  • biconcave shape to increase surface area for diffusion, and increase the cell flexibility for it to fit through narrow capillaries
  • no nucleus so there is more space to hold haemoglobin to increase transport of oxygen
35
Q

what is the structure & function of neutrophils?

A
  • has a lobed nucleus & granular cytoplasm
  • they are flexible to enable them to surround pathogens and engulf them
  • they contain lysosomes filled with the hydrolytic enzyme lysozyme
  • made from stem cells in the bone marrow
36
Q

what is the structure & function of sperm cells?

A
  • the flagellum contains many mitochondria to release energy for movement to enable the sperm cell to move towards the egg cell
  • the acrosome in the head of the cell contains digestive enzymes to digest the wall of the egg cell so the sperm can penetrate and fertilise the egg cell
37
Q

what is the structure & function of the palisade cells?

A
  • located in the mesophyll tissue layer of leaves
  • rectangular, tightly packed cells that contain many chloroplasts to absorb and maximise light energy for photosynthesis
  • thin cell walls to reduce diffusion distance of carbon dioxide
38
Q

what is the structure & function of guard cells?

A
  • pair of cells that have flexible walls, more so on one side, which results in the cells bending when turgid to open stomata, and closing when flaccid, this helps control water loss via transpiration
39
Q

what is the structure & function of squamous epithelial cells?

A
  • single layer of flat cells in contact with the basement membrane of the epithelium, this provides a short diffusion distance
  • these form the linings of the lungs
40
Q

what is the structure & function of ciliated epithelial cells?

A
  • they have hair-like projections that sway to move substances, such as mucus, out of the lungs
  • goblet cells are also located within the epithelium and these cells release mucus to trap molecules e.g. dust in the trachea
41
Q

What is the structure & function of cartilage?

A
  • a connective tissue that is firm & flexible
  • located in the outer ear, nose, and the end of the bones
  • provides structural support, and it prevents the bones from rubbing together which would damage them
  • made up of elastin & collagen fibres, and chondrocyte cells within an extracellular matrix
42
Q

What is the structure & function of muscle?

A
  • composed of tissues that can contract & relax to create movement
  • skeletal muscles cause the skeleton to move and are made up of myofibrils containing the proteins actin & myosin
  • smooth muscle is located within organs
  • cardiac muscle is within the heart
  • muscles have multiple fibres connecting with connective tissues in between
43
Q

What is the structure & function of the xylem?

A
  • the xylem is cells that make up part of the vascular bundle in plants which are responsible for transporting water & mineral ions
  • the tissue is made up of elongated, hollow dead cells, with lignin walls to strengthen and waterproof the walls
  • xylem tissues are made from the stem cells in the meristem
44
Q

What is the structure & function of the phloem?

A
  • the cells that make up part of the vascular bundle which are responsible for transporting organic substances made in photosynthesis
  • have sieve tube element cells, which have perforated end walls, and are lacking most organelles to make transport of sugars easier
  • have companion cells which contain organelles to provide resources for the sieve tube elements
  • phloem sieve tubes are made from the stem cells in meristem
45
Q

What are stem cells?

A

Undifferentiated cells that can self-renew (continually divide) and become specialised

46
Q

What are the 4 different types of stem cells?

A
  • totipotent
  • pluripotent
  • multipotent
  • unipotent
47
Q

What are totipotent cells?

A
  • cells that can divide and produce any type of body cell
  • during development they translate only part of their DNA which results in cell specialisation
  • they occur only for a limited time in early mammalian embryos
48
Q

What are pluripotent cells?

A
  • they are found in embryos and can become almost any type of cell
  • used in research with to prospect of using them to treat human disorders
49
Q

What are the issues with using pluripotent cells to treat human disorders?

A
  • sometimes treatment doesn’t work
  • stem cells can continually divide to create tumours
  • ethically, there is a debate on whether it is right to make a therapeutic clone of yourself to make an embryo to get the stem cells to cure a disease, and then destroy the embryo
50
Q

What are multipotent cells?

A
  • found in mature mammals and can divide to form a limited number of different cell types
  • they can differentiate into a limited number of cells
51
Q

What are unipotent cells?

A
  • found in mature mammals and can divide to form a limited number of different cell types
  • can only differentiate into one type of cell
52
Q

What are the potential uses of stem cells?

A

They can be used in both research and medicine, these uses include:
- repairing damaged tissue
- treatment of neurological conditions such as Alzheimer’s and Parkinson’s
- research into developmental biology

biology (12 decks)

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