Cell Division Flashcards
(106 cards)
1
Q
How many pairs of chromosomes do we have
A
23
2
Q
How many chromosomes in haploid
A
23
3
Q
How many chromosomes are in diploid
A
46
4
Q
What is a zygote
A
Fertilised egg cell
5
Q
DNA + protein =
A
Histone
6
Q
DNA + hisstones =
A
Chromatin
7
Q
What are chromatids
A
Short arms
8
Q
What is the middle of a chromosome called
A
Centromere
9
Q
What is the cell cycle
A
The process of how cells replicate and divide
10
Q
What are the stages of the cell cycle
A
G1
S
G2
M- PMAT
11
Q
What stages are involved with interphase
A
G1
S
G2
12
Q
What is involved in the G1 phase
A
- Growth phase
- Normal metabolic roles
- Checkpoint control mechanism ensures that the cell is ready to enter the S phase
- cells grow in size
- organelles duplicate
- transcription of genes to make RNA occurs
13
Q
What is involved in the s stages
A
-DNA replication
-when all chromosomes have been duplicated each one consists of a pair of identical sister chromatids
-rapid phase
-
14
Q
What is involved in the G2 phase
A
- Growth and preparations for mitosis
- special chemicals ensure that the cell is ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and in formation of the spindle fibre
15
Q
What is involved in the m phase
A
A check point chemical triggers condensation of chromatin
- cell growth stops
- include PMAT
- includes cytokinesis
16
Q
Describe G zero
A
A resting place triggered during early G at the restriction point by a checkpoint chemical
17
Q
When do mutations occur
A
When cells are not check pointed properly
18
Q
What are checkpoints
A
Biological restrictions / traffic point
19
Q
Where are the two main checkpoints
A
G1/S
G2/M
20
Q
What are the purpose of check points
A
To prevent uncontrolled divisions that would lead to tumours
To detect and repair damage to DNA
21
Q
Because the cell cycle happens in a specific sequence it ensures that
A
The cycle cannot be reversed
The DNA is only duplicated once during each cell
22
Q
What are the 4 stages of mitosis
A
Prophase
Metaphase
Anaphase
Telophase
23
Q
Describe prophase
Mitosis
A
- nucleolus begins to fade
- the centrioles duplicate and move to opposite poles
- the centrioles form spindle fibres
- chromosomes shorten and thicken, becoming visible
- the nuclear envelope begins to disintegrate
24
Q
Describe metaphase
Mitosis
A
- chromosomes line up along the equator of the cell
- one chromatid of each pair lies on either sides
- spindle fibres attach to the centromeres
25
Describe anaphase
Mitosis
- the spindle fibre begin to contact
| - sister chromatids are pulled apart to and live to opposite poles of the cell
26
Describe telophase
Mitosis
- separation of chromatid is complete
- spindle fibres disintegrate
- each chromatid is now a chromosome
- the nuclear envelope reforms around each group of chromosomes
- the cell divides alone the waist via cytokinesis
- both daughter cells formed are identical
27
What does homologous mean
Mitosis
Chromosomes which are about the same size and contain the same types is genes in same locations. Same alleles
28
What is meiosis
Type of nuclear division that results in the the formation is cells containing half the number of chromosomes of each patent cell
Formation of gametes
29
How meiosis produces genetic variation
- crossing over during prophase 1 suffers alleles
- independent assortments of chromosomes in anaphase 1 leads to random distribution of material and paternal chromosomes of each pair
- haploid gametes are produced which can undergo random fusion with gametes derived from another organism of the same species
30
What are the stages of meiosis
```
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2
```
31
Describe prophase 1
Meiosis
- chromatin condenses and each chromosome super coils
- nuclear envelope breaks down , spindle threads of Tubulin protein form from the centrioles
- chromosomes come together in their homologous pairs
- each member of the pair consists of two chromatids
- crossing over occurs
32
Describe metaphase 1
Meiosis
- pair of homologous chromosomes, still in their crossed over state attach along the equator of the spindle
- attaches to a spindle thread by its centromere
- homologous pairs are arranged randomly with its members of each pair facing opposite poles of the cell
- the way they line up in the metaphase determines how they will segregate independently when pulled apart during anaphase
33
Describe anaphase 1
Meiosis
- 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 chromosomes consists of two chromatids
- the crossed over area separates from each other , resulting in swapped area of chromosomes and allele shuffling
34
Describe telophase 1
Meiosis
- two new nuclear envelopes form around each set of chromosomes and the cell divides by cytokinesis
Chromosomes uncoil
-each new nucleus contains half the original number of chromosomes but each chromosomes consists of two chromatids
35
Describe prophase 2
Meiosis
- if the nuclear envelopes have reformed then they now break down
- chromosomes coil and condense each one consisting of two chromatids
- chromatids of each chromosome are no longer identical due to crossing over in prophase 1
- spindles form
36
Describe metaphase 2
Meiosis
- chromosomes attach by their new centromere to the equator of the spindle
- chromatids of each chromosome are randomly arranged
- the way that hey are arranged will determine how the chromatids separate during anaphase
37
Describe anaphase 2
Meiosis
- the centromere divides
- 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 and therefore randomly segregated
38
Describe telophase 2
Meiosis
- nuclear envelope form around each of the four haploid Nuclei
- the two cells now divide to give us 4 haploid cells
39
Define differentiation
Process by which stem cells become specialised into different types of cells
40
Define epithelial cells
Cells that constitute lining tissues
41
What are erythrocytes
Red blood cells
42
What are neutrophil
Type of white blood cells that is phagocytic
43
Define stem cells
Unspecialised cells able to express all of its genes and divide by mitosis
44
Erythrocytes are adapted to carry out their function in several ways :
- carry oxygen from the lungs to respiring cells
- small
- large SA/v ratio , so oxygen can diffuse across their membranes
- biconcave shape to increase SA/V ratio
- flexible , so can bend through narrow capillaries
45
Describe neutrophils
Twice the size of erythrocytes
- travel towards infection sites by chemotaxis
- their function is to ingest bacteria and some fungi by phagocytosis
46
What is spermatozoa
Sperm cells
47
How are spermatozoa specialised
- -mitochondria , aerobic respiration and ATP energy
- small long thin , move easily
- acrosome - enzymes released to digest egg
48
Where are epithelial cells located
Found in the outside of your body and on the inside
| Eg - walls of alveoli , exchange surfaces , intestines
49
Squamous epithelial cells are
Flatterned in shape
50
Name the specialised plant cells
```
Upper epidermis
Palisade mesophyll
Xylem
Phloem
Lower epidermis
Cuticle
Spongy mesophyll
Guard cell
Stoma
```
51
Palisade cells are well adapted for photosynthesis because
- long and cylindrical so they pack together closely but with space so gases can diffuse
- contain chloroplasts
- large vacuole so chloroplasts are positioned nearer to the top of the cell
- contain cytoskeleton threads and motor proteins to move chloroplasts
52
Describe guard cells
Water enters the guard cells from neighbouring epidermal cells by osmosis
- the guard cells swell , causing them to open , as they open air can enter the spaces within the layer of cells beneath the palisade layer
- gaseous exchange can happen
- water vapour can exit
53
What are root hair cells
Are epidermal cells on the pure layer is young plant roots
54
Describe root hair cells
- hair like projections greatly increase the surface area for absorption of water and mineral ions
- minerals are actively transported
- produce ATP needed for active transport
55
Define tissue
A group of cells working together to perform a specific function
56
What are the body's 4 main body tissues
Epithelial
Connective tissues
Muscle tissues
Nervous tissues
57
Define connective tissues
These hold structures together and provide support t
58
Define muscle tissue
Made of cells that are specialised to contract and cause movement
59
Define nervous tissues
Made of cells specialised to conduct electrical impulses
60
Epithelial tissues cover
Skin , respiratory system , walls of organs
61
Characteristics is epithelial tissues
- made entirely of cells
- specialised to carry out its function of protection , absorption , filtration , excretion and secretion
- shirt cell cycles
- some have smooth surfaces , but some have cilia or microvilli
62
What is cilia
Are hair like organelle some of which beat and propel substances along the epithelial it faces
63
What are microvilli
Are extensions of the plasma membrane to increase its surface area
64
Describe connective tissues
Is widely distributed in the body. It consists of a non living extra cellular matrix containing proteins and polysaccharides
This matrix separates the living cells within the tissue and enables it to withstand forces such as weight
65
What are the three types of cartilage
Hyaline
Fibrous
Elastic
66
Describe elastic cartilage
Makes up the outer ear and the epiglottis
67
Describe fibrous cartilage
Occurs in discs between vertebrae in the back nine and the knee joint
68
Describe hyaline cartilage
Forms the embryonic skeleton , covers the end of long bones in adults , joins ribs to the sternum and found in the nose , trachea and larynx
69
Muscle tissues allow movement , what are the 3 types
Skeletal
Cardiac
Smooth muscle
70
Describe skeletal muscles
Packaged by connective tissue sheets joined to hone by tendons , these muscles when they contract cause bones to move
71
Describe cardiac muscles
Makes up the walls of the heart and allows the heart to beat and pump blood
72
Describe smooth muscles
Occur in the walls is intestine, blood vessels , uterus and urinary tracts , and it propels substances along these tracks
73
Define meristem
Area of unspecialised cells within a plant that can divide and differentiate into other cell types
74
Define organ
Collection of tissues working together to perform a function
75
Define phloem
Tissue that carries products of photosynthesis ; in solution within plants
76
Define xylem
Tissues that carries water and minerals ions from the roots to all parts of the plant
77
Describe epidermal tissues
This is equivalent to epithelial tissues in animals. It consists of flattered cells , lack chloroplast and form a protective covering over leaves , stems and roots
78
Describe meristematic tissues
Contain stem cells. It is from this tissue that all other plant tissues are derived by cell differentiation. It is found at roots and shoot tips and in the cambium of vascular bundles
79
Characteristics of meristems
- thin walls containing little cellulose
- do not have chloroplasts
- do not have a large vacuole
- can divide by mitosis and differentiate into other types of cells
80
Explain how cambium cells differentiate into xylem vessels
- lignin is deposited in their cell walls to reinforce and waterproof then
- the ends of the cell breaks down so that the xylem forms continuous columns with wide lumens to carry water and dissolves mineral
81
Explain how other cambium cells differentiate into phloem sieve tubes or companion cells
- -sieve tubes lose most of the organelle and sieve plates develop between then
- companion cells retain their organelles and continue metabolic functions to provide ATP for active loading of sugars into the sieve tubes
82
Name the 4 plant organs
Leaf
Root
Stem
Flower
83
What is the main function of the leaf
Photosynthesis
84
What's the main function of the root
- anchorage in soil
- - absorption of mineral ions
- storage
85
What's the function of stems
- Support
- holds leaves up so their exposed to more sunlight
- transport is water and minerals
86
What's the function of the flower
- sexual reproduction
87
Define organ system
A bummer is organs working together to carry out an overall life function
88
What are the organ systems in our body
```
Digestive
Circulatory
Respiratory
Urinary
Integumentary
Musculoskeletal
Immune
Nervous
Endocrine
Reproductive
Lymph
```
89
The digestive system
Organs involved and examples of life processes
Oesophagus , stomach , intestines , liver
Nutrition to provide ATP and materials for growth and repair
90
Circulatory system
Organs involved and processes involves
Heart and blood vessels
Transport to and from cells
91
Respitory system
Organs and life processes
Airways , lungs , diaphragm and intercostal muscles
Breathing and gaseous exchange excretion
92
Urinary system
| Organs involved and life processes
Kidneys , uterus and bladder
Excretion and osmoregulation
93
Integumentary system
Organs involved , processes
Skin hair nails
Waterproofing ,protection , temperature regulation
94
Musculoskeletal system
Organs and processes
Skelton , skeletal muscles
Support
Protection
movement
95
Immune system
Organs and processes
Bone marrow , skin , blood
Protection against pathogens
96
Nervous system
Organs processes
Brain , spinal Cord , nerves
Communication , control , coordination
97
Endocrine
Organs and processes
Glands that make hormones
Communication
Control
Coordination
98
Reproductive
Organs and processes
Testes , Penis , ovaries , uterus , vagina
Reproduction
99
Lymph
Organ and processes
Lymph nodes and vessesls
Transport of fluid back to the circulatory system and is important in resisting infections
100
What are stem cells
Unspecialised cells able to express all of its genes and divide by mitosis
101
Describe stem cells
Are undifferentiated cells , capable of becoming any type of cell in the organism
- describe as pluripotent
- able to express all their genes
- can divide my mitosis
- used in medical
102
What are the sources of stem cells
Embryonic stem cells
Stem cells In the umbilical cord
Adult stem cells
Induced pluripotent stem cells
103
What are induced Pluripotent stem cells
Developed in laboratories by reprogramming differentiated cells to switch in certain key genes and become undifferentiated
104
Where are embryonic stem cells
Present in an early embryo formed when the zygote begins to divide
105
What are adult stem cells
Are found I developed tissues such tissues such as blood , brain , muscle , bone
They act like a repair system because they are renewing source of undifferentiated cells
106
What are the potential uses in research and medicine
Bone marrow transplant
Drug research
Development in biology
Repair of damaged tissue or replace not of lost tissues
