Cell Division, Diversity And Differentiation

Question 1

In the cell cycle,
M is the ________
G, S are part of the ______

Answer 1

division phase (mitosis/meiosis)
interphase

Question 2

What are checkpoints in the cell cycle for?

Answer 2

prevent uncontrolled division (lead to tumors), repair damage to DNA

Question 3

What happens in the M phase of the cell cycle?

Answer 3

chromatin condenses
the checkpoint ensures that the cell is ready for mitosis
cell growth stops and mitosis occurs

Question 4

What happens in the G₀ (gap 0) phase of the cell cycle?

Answer 4

resting
apoptosis (programmed cell death)
differentiation

Question 5

What happens in the G₁ phase of the cell cycle?

Answer 5

growth phase, cell grows
checkpoint ensures ready to enter S phase
transcription of genes to RNA
organelles duplicate

Question 6

What happens in the S (synthesis) phase of the cell cycle?

Answer 6

rapid phase (reduces mutation)
chromosomes unwind
DNA replicates
genes that are active in all cells replicate first

Question 7

What happens in the G₂ phase of the cell cycle?

Answer 7

chemicals ensure the cell is ready for mitosis
stimulate proteins which make chromosomes condense to spindle
cells grow

Question 8

Mitosis prophase is when…

Answer 8

2 sister chromatids shorten, thicken as DNA coils, nuclear envelope breaks down,
centrioles move to poles,
cytoskeleton protein threads form spindle between centrioles

Question 9

Mitosis metaphase is when..

Answer 9

pairs of chromatids attach to spindle threads in middle and are attached by their centromeres.

Question 10

Mitosis anaphase is when…

Answer 10

pairs of chromatids are pulled apart, the centromere splits,
motor proteins pull chromatids in opposite directions to poles
they are now chromosomes

Question 11

Mitosis telophase is when…

cytokinesis is when…

Answer 11

chromosomes reach the poles
nuclear envelope forms around the chromosomes
now there are 2 identical nuclei

the cytoplasm splits leading to 2 new daughter cells.

Question 12

Meiosis is…

Answer 12

a type of nuclear division that results in the formation of gametes.

Question 13

Haploid

Answer 13

one set of chromosomes (23)

Question 14

2 gamete nuclei fuse = …

Answer 14

diploid zygote

Question 15

Homologous chromosomes

Answer 15

matching
containing same genes, same place
same genes but different alleles (variants)

Question 16

What happens in the S phase of interphase, in Meiosis?

Answer 16

chromosomes are duplicated as the DNA is replicated
now, each chromosome consists of 2 sister chromatids
in meiosis, chromosomes pair with homologous pair.

Question 17

Meiosis prophase 1

Answer 17

chromatin condenses, supercoils
nuclear envelope breaks down
microtubules form from centrioles
chromosomes come together in homologous pairs, each member consists of 2 chromatids

crossing over occurs (non-sister chromatids wrap, swap sections, alleles shuffled)

Question 18

Meiosis metaphase 1

Answer 18

line in middle, attach to spindle thread by centromere

independent assortment occurs (homologous pairs arranged randomly) = determines how pulled apart

Question 19

Meiosis anaphase 1

Answer 19

pair of homologous chromosomes pulled apart by motor proteins
each chromosome has 2 chromatids

Question 20

Meiosis telophase 1

and after?

Answer 20

nuclear envelope forms
cell divides by cytokinesis

then there’s a short interphase when chromosomes uncoil (each chromosomes = 2 chromatids)

Question 21

Meiosis prophase 2

Answer 21

nuclear envelope breaks down
chromosomes coil and condense
chromatids of each chromosomes are no longer identical
spindles form

Question 22

Meiosis metaphase 2

Answer 22

chromosomes attach by centromere to middle of the spindle

chromatids randomly arrange

Question 23

Meiosis anaphase 2

Answer 23

centromeres divide
chromatids pulled apart by motor proteins towards poles
chromatids randomly segregated

Question 24

Meiosis telophase 2

Answer 24

nuclear envelope forms around each 4 haploid nuclei

2 cells now divide to give 4 haploid cells

Question 25

How does Meiosis produce variation?

Answer 25

``` crossing over (prophase 1) independent assortment (anaphase 1 and 2) or metaphase random haploid gametes fuse ```

Question 26

Why do organisms need specialised cells for particular functions?

Answer 26

Multicellular organisms are large so have a small SA to V ratio. This means that not all cells are in direct contact with the external environment.

Question 27

Zygote

Answer 27

undifferentiated cell, stem cell

Question 28

Differentiation

Answer 28

stem cells become specialised into different types genes switch on or off so that proportions of organelles differ, the shape of the cell changes, the contents of the cell changes.

Question 29

How are erythrocytes (RBC) adapted to their function?

Answer 29

large SA:V because they are small (O₂ can diffuse and reach all regions of the cell) biconcave shape (large SA:V) flexible (change shape, easily travel through capillaries organelles lost at differentiation (no nucleus, more space for haemoglobin molecules)

Question 30

How are neutrophils adapted to their function? | ingest invading pathogens

Answer 30

twice the size of RBS multi-lobed nucleus attracted to infection sites by chemotaxis ingest by phagocytosis

Question 31

How are spermatozoa adapted to their function?

Answer 31

``` many mitochondria (aerobic respiration, ATP for undulipodium to move) small, long, thin (move easily) enzymes released from acrosome (head) = lysosome (digest covering of ovum and allow entry) head contains haploid male gamete nucleus and little cytoplasm ```

Question 32

How are epithelial cells adapted to their function? (lining tissue in alveoli, capillaries)

Answer 32

squamous epithelial cells (flattened) | many have cilia

Question 33

How are palisade cells adapted?

Answer 33

long, cylindrical (pack closely) small spaces between (air circulate) large vacuole (chloroplasts near top so reduce diffusion distance for CO₂) many chloroplasts (for photosynthesis) cytoskeleton threads, motor proteins (move chloroplasts to upper surface

Question 34

How are guard cells adapted? (in lower epidermis [outer layer of cells covering organism])

Answer 34

light energy used to produce ATP ATP transports potassium ions to guard cells (lowers water potential so water enters from other cells by osmosis) cells swell and stoma enlarges stomata opens to let air enter spaces within layer of cells below palisade gaseous exchange occurs, CO₂ into palisade (photosynthesis) O₂ out palisade, out stomata

Question 35

How are root hair cells adapted? (epidermal cells)

Answer 35

hair-like projections (increases SA to absorb from soil) mineral ions actively transported into cells (lower water P so water follows) carrier proteins in plasma membrane (actively transports mineral ions produce ATP (for active transport)

Question 36

What are the 4 main animal tissue types?

Answer 36

epithelial connective muscle nervous

Question 37

What are epithelial tissues, their function and structure?

Answer 37

covers and lines surfaces cells close, continuous sheets no blood vessels receive nutrients from diffusion from tissue fluid short cell cycles protection, absorption, filtration, excretion, secretion e.g. skin

Question 38

What are connective tissues for, and structure?

Answer 38

hold structures provide support has non-living extra cellular matrix containing proteins and polysaccharides matrix separates living cells within tissue and enables it to withstand forces like weight e.g. blood bone, cartilage

Question 39

________ _____ in cartilage are called _____________

Answer 39

immature cells | chondroblasts

Question 40

What happens when chondroblasts divide by mitosis?

Answer 40

secrete extracellular matrix | matrix synthesised and chondroblasts becomes mature, less active chondrocytes which maintain the matrix

Question 41

What are the 3 types of cartilage?

Answer 41

Hyaline Fibrous Elastic

Question 42

What is Hyaline cartilage?

Answer 42

``` it forms embryonic skeletons covers ends of long bones in adults joins ribs to sternum in nose trachea (c-shaped rings) larynx (voice box) ```

Question 43

What is Fibrous cartilage?

Answer 43

occurs in discs between vertebrae in the backbone | and knee joint

Question 44

What is Elastic cartilage?

Answer 44

makes up outer ear (pinna) and epiglottis (flap that closes over larynx when swallow)

Question 45

Tell me about muscle tissues, Anna.

Answer 45

cells specialised to contract and cause movement well vascularised (blood vessels) fibres are elongated contain myofilaments that allow muscle tissue to contract

Question 46

3 muscle tissues?

Answer 46

skeletal muscle - packaged by connective tissue sheets, joined to bones by tendons, cause movement cardiac muscle - walls of heart, allow to beat and pump blood smooth muscle - walls of intestine, blood vessels, uterus, urinary tracts, propels substances along these tracts

Question 47

Epidermal plant tissues (equivalent to epithelial in animals)

Answer 47

flattened cells lack chloroplasts (apart from guard cells) protective covering some contain waxy substance that forms cuticle (in dry environments)

Question 48

Vascular plant tissues

Answer 48

transport (xylem, phloem) xylem transports water and minerals from roots to plant phloem sieve tubes transfer products of photosynthesis from leaves to plant

Question 49

Meristematic plant tissues

Answer 49

contain stem cells (meristem) from this tissue, all plant tissues are derived at root, shoot tips, cambium of vascular bundle (these areas called meristems) cells in meristems have thin walls, little cellulose, no chloroplasts, not large vacuole, divide by mitosis so differentiate.

Question 50

What happens when most plant cells mature?

Answer 50

develop large vacuole, rigid cell wall so can't divide | new cells arise at meristems by mitosis

Question 51

How do cambium cells differentiate into xylem vessels?

Answer 51

lignin (woody substance) deposits in cell wall to reinforce it and make waterproof, but also kills cells end of cells break down so xylem forms in columns with wide lumen.

Question 52

How do cambium cells differentiate into phloem sieve tubes?

Answer 52

lose most organelles, sieve plates develop between them

Question 53

How do cambium cells differentiate into companion cells?

Answer 53

retain organelles, continue metabolic functions, provide ATP for active loading of sugars into sieve tubes

Question 54

``` Digestive system Circulatory system Respiratory system Urinary system Immune system Nervous system + Endocrine system Reproductive system ```

Answer 54

nutrition to provide ATP and materials for growth and repair transport to and from cells breathing, gaseous exchange excretion and osmoregulation protect against pathogens communication, control and coordination reproduction

Question 55

Integumentary system Musculo-skeletal system Lymph system

Answer 55

(skin, hair, nails) waterproof, protection, temp regulating (skeleton, skeletal muscles) support, protection, move (lymph nodes and vessels)transports fluids back to circulatory system, resists infection

Question 56

Pluripotent

Answer 56

undifferentiated cell capable of becoming any type

Question 57

What are 4 sources of stem cells?

Answer 57

embryonic stem cells (formed when zygote begins to divide) umbilical-cord blood adult stem cells (developed in tissues) (blood, brain, bone) like repair system induced pluripotent stem cells (iPS cells) (in labs by reprogramming differentiated cells to switch on key genes so become undifferentiated)

Question 58

What are 4 stem cell uses?

Answer 58

bone-marrow transplants: to treat diseases of the blood, immune system and restore blood after cancer treatment drug research: test on differentiated cells derived from stem developmental biology: study how cells develop, function, what's wrong when diseased. Find out if can extend capacity that embryos have for growth and repair, into later life repair damaged tissues/replace: treat mice with type 1 diabetes, research to develop in humans, bone-marrow can treat liver disease, could grow organ so no need for immunosuppressants.