Module 2: Foundatioms In Biology - Cell Division, Cell Diversity and Cellular Organisation 🟢 Flashcards
(41 cards)
1
Q
What is the cell cycle and outline it’s stages
A
Regulated cycle of division with intermediate growth periods
- Interphase (G1, S, G2)
- Nuclear division- mitosis or meiosis
- Cytokinesis
2
Q
Interphase
A
- Longest stage in the cell cycle
G1: cell synthesises proteins for replication e.g. tubulin for spindle fibres & cell size doubles.
S: DNA replicates = chromosomes consist of 2
sister chromatids joined at a centromere.
G2: Organelles divide.
3
Q
Mitosis
A
Produces 2 genetically indentical daughter cells for:
-growth
- cell replacement/tissue repair
- asexual reproduction
4
Q
A
5
Q
What are the 4 stages of mitosis ?
A
1.Prophase
2. Metaphase
3. Anaphase
4. Telophase
(PMAT)
6
Q
Prophase
A
- chromosomes condense and become visible
- nuclear envelope disintegrates
- in animals - centrioles separate and spindle fibre structure forms
7
Q
Metaphase
A
- chromosomes align along equator of cell
- spindle fibres released from poles now attach to centromere and chromatid
8
Q
Anaphase
A
- spindle fibres contract (using ATP) to pull chromatids, centromere first , towards opposite poles of cell
- centromere divides in two
9
Q
Telophase
A
- chromosomes at each pole become longer and thinner again
- spindle fibres disintegrate and nucleus reforms
10
Q
Cytokinesis
A
The division of the cytoplasm to create two new cells
11
Q
Mitotic index
A
- used to determine proportion of cells undergoing mitosis
- calculated as a percentage or decimal
Mitotic index = number of cells in mitosis/the total number of cells
- for percentage x100
12
Q
Meiosis
A
Two nuclear divisions that result in four genetically different haploid daughter cells
13
Q
Haploid
A
One copy of each chromosome
14
Q
Diploid
A
Two copies of each chromosome
15
Q
Genetic differences introduced by meiosis
A
- independent assortment of homologous chromosomes
- crossing over
16
Q
Crossing over
A
- chromosomes condense and thicken in prophase
- Homologous chromosomes pair to form bivalents
- crossing over can occur between the chromatids of bivalents
- this results in new combinations of alleles in the resulting gamete
17
Q
Independent assortment
A
- homologous pairs of chromosomes line up opposite each other on either side of the equator during metaphase
- it is random which side of the equator the maternal or paternal pairs align
- As a result , each gamete receives a different combination of maternal and paternal chromosomes
18
Q
Erythrocytes
A
- these are red blood cells
- they have a biconcave shape to increase the surface area for diffusion and increase the cell flexibility to fit through narrow capillaries
- these cells have no nucleus to maximise oxygen-carrying capacity
- they are made from stem cells in the bone marrow
19
Q
Neutrophils
A
- a type of white blood cell
- have a lobed nucleus and granular cytoplasm
- these cells are flexible to enable them to surround pathogens and engulf them
- they contain lysosomes filled with the hydrolytic enzyme , lysozyme
20
Q
Sperm cells
A
- the flagellum contains many mitochondria to release energy for locomotion to enable them 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
21
Q
Palisade cells
A
- located in the mesophyll tissue layer of leaves
- palisade cells are rectangular , tightly packed cells that contain many chloroplasts to absorb and maximise light energy for photosynthesis
- they have thing cell walls to reduce the diffusion distance of carbon dioxide
22
Q
Root hair cells
A
- cells on the surface of roots
- long projections to increase surface area for osmosis of water and active transport of mineral ions
- thin cell wall to reduce the diffusion distance
23
Q
Guard cells
A
- these pair of cells have flexible walls , more so on one side, which results in the cells bending when turgid to open stomata and closing when flaccid and this helps control water loss by transpiration
24
Q
Squamous epithelial cells
A
- usually only a single layer of flat cells in contact with the basement membrane of epithelium
- this provides a short diffusion distance
25
Ciliated epithelial cells
- these cells have hair-like projections that say to move substances , such as mucus , Out of the lungs , or an egg in the oviduct
- goblet cells are also located within the epithelium and these release mucus to trap molecules
26
Cartilage
- this is a connective tissue that is firm and flexible
- it is located in the outer ear,nose and the end of bones
- it provides structural support and it prevents the bones from rubbing together and causing damage
- it is made up of collagen and elastin fibres, and chondrocyte cells with an extracellular matrix
27
Muscle
Composed of tissue that can contract and relax to create movement
- muscles have multiple fibres connecting with connective tissues in between
28
Xylem
- the cell that make up part of the vascular bundle in plants responsible for transporting water andmineral ions
- the tissue is made up of elongated , hollow dead cells, with lignin in the walls to strengthen and waterproof the walls
- xylem tissues are made from the stem cells in the meristem
29
Phloem
Form part of the vascular bundle in
- transport organic substances made in photosynthesis
- made of sieve tube element cells and companion cells
- plasmodesmata: gaps between cell walls where the cytoplasm links, allowing substances to flow
30
Sieve tube elements in phloem
- cells have perforated end walls
- lacking most organelles to make the transport of sugars easier
31
Stem cells
- stem cells are undifferentiated cells that can self-renew (continually divide)and become specialised
- different types of stem cells have different differentiation abilities :
- totipotent
- pluripotent
- multipotent
- unipotent
32
Totipotent cells
- can divide and produce any type of body cell
- during development, totipotent cells transport only part of their DNA, resulting in cell specialisation
- totipotent cells only occur for a limited time in mammalian embryos
33
Pluripotent cells
Are found in embryos and can become almost any type of cell
- they are often used in research
34
Multipotent and unipotent cells
- found in mature mammals
- can divide to form a limited number of different cell types
35
Potential uses of stem cells
- can be used in both research and medicine:
- repairing damaged tissues
- treatment of neurological conditions such as Alzheimer’s or Parkinson’s
- research into developmental biology
36
What are homologous chromosomes
Pair of chromosomes with genes at the same locus. 1 maternal & 1 paternal.
Some alleles may be the same while others are different.
37
What is a transcription factor
A protein that controls the transcription of genes so that only certain parts of the
DNA are expressed, e.g. in order to allow a cell to specialise.
38
Describe the 2 groups of specialised cells in blood
Erythrocytes (red blood cells): biconcave, no nucleus, lots of haemoglobin to carry oxygen.
Leucocytes (white blood cells): lymphocytes, eosinophils, neutrophils to engulf foreign material, monocytes.
39
Describe the structure of a vascular bundle
- phloem tissue
- xylem tissue
- cambium (meristematic tissue)
Check photo
40
Name the 3 types of muscle in the body and where they are located
- cardiac: exclusively found in heart
- smooth: walls of blood vessels and intestines
- Skeletal: attached to incompressible skeleton by tendons
41
Describe the gross structure of skeletal muscle
Muscle cells are fused together to form bundles of parallel muscle fibres (myofibrils).
Arrangement ensures there is no point of weakness between cells.
Each bundle is surrounded by endomysium: loose connective tissue with many capillaries.
