Cell Structure Flashcards
(91 cards)
1
Q
what do cells do in order to become specialised
A
differentiation
2
Q
how are types of cells different to each other
A
they all contain the same genetic information but depending on what role a cell needs to play
3
Q
what happens to a cell when it differentiates
A
it develops a structure and composes subcellular structures which enables it it carry out a certain function
4
Q
what are adult stem cells and what are they mainly involved in
A
undifferentiated cells that retain their ability to specialise throughout adulthood
involved in replacing and repairing cells
5
Q
what is a specialised cell
A
those which have developed certain characteristics in order to perform particular functions. these differences are controlled by the nucleus
6
Q
what does a ciliated cell do and what are its adaptations
A
- movement of mucus in the trachea and bronchi
has extensions of the cytoplasm at the surface of the cell to form hair-like structures called cilia
7
Q
what does a nerve cell do and what are its adaptations
A
- conduction of impulses
- long so it can stretch to different parts of the body
- cell has extensions and branches so that it can communicate with other nerve cells and muscles and glands
- the axon is covered with a fatty sheath which insukates the nerve cell and speeds up the nerve impulse
8
Q
what does a nerve cell do and what are its adaptations
A
conduction of impulses
- long so that they can stretch to and from different parts of the body
- cell has extensions and branches so that it can communicate with other nerve cells, muscles and glands
- the axon has a fatty sheath to insulate it and speed up the nerve impulse
9
Q
what does a red blood cell do and what are its adaptations
A
transport of oxygen
- biconcave disk
- contains haemoglobin
- contains no nucleus
10
Q
what does a sperm cell do and what are its adaptations
A
reproduction
- haploid nucleus
- tail
- packed with mitochondria
- contains digestive enzymes in the acrosome to penetrate the egg
11
Q
what does a egg cell do and what are its adaptations
A
reproduction
- contains a lot of cytoplasm which contains a lot of nutrients
- haploid nucleus
- cell membrane has the ability to shut out more sperm after one has got through
12
Q
what are some examples of specialised cells in animals
A
ciliated
nerve
egg
sperm
red blood
13
Q
what are some examples of specialised cells in plants
A
root hair cell
xylem vessel
palisade mesophll cell
14
Q
what does a root hair cell do and what are its adaptations
A
absorption of water an minerals from soil
- root hair increases surface area
- walls are thin
- no chloroplasts present
15
Q
what does a palisade mesophyll cell do and what are its adaptations
A
photosynthesises
- column shaped so they can be closely packed together and maximise absorption of sunlight
- contains many chloroplasts for maximum photosynthesis
16
Q
what does a xylem vessel do and what are its adaptations
A
conducts water through plant and supports it
- no top or bottom walls so that between vessels there is a continuous column
- cells are dead to allow free passage of water
- lignin cell walls to keep support
17
Q
what is a stem cell
A
an undifferentiated cell that is capable of diving to produce more stem cells or other cell types through differentiation
18
Q
what are the three types of stem cell
A
embryonic
adult
meristem
19
Q
where are embryonic stem cells found
A
on the inside layer of an embryo
20
Q
where are adult stem cells found
A
bone marrow
skin
umbilical cord blood
other organs such as liver and brain
21
Q
what is similar about embryonic and meristem cells
A
they are both undifferentiated and unspecialised
22
Q
why are adult stem cells not entirely useful
A
they have a limited ability to differentiate
23
Q
what cells can be produced from an embryonic stem cell
A
all the types of specialised cell found in the body
24
Q
what cells can be produced from an adult stem cell found in the skin
A
skin cells and hair follicles
25
what cells can be produced from meristem cells
one cell has the ability to produce a whole new plant
26
where are meristem cells found
in the tips of roots and shoots (the growing regions of plants)
27
what cells can be produced from an adult stem cell found in the bone marrow
mainly blood cells (red blood cells, cells of the immune system)
28
what cells can be produced from an adult stem cell found in the umbilical cord blood
cells of the blood (red and white), muscle and nerve tissue
29
what cells can be produced from an adult stem cell found in other organs such as the liver and brain
cells found in these organs
30
what does the term totipotent mean
they can form all of the different tissues and organ needed during development
embryonic stem cells are totipotent
31
what is the main role of adult stem cells
to replace cells lost through damage or to produce new cells for growth
32
what is type 1 diabetes
inability of the pancreas to produce insulin to control blood sugar levels
33
how can stem cells treat type 1 diabetes
stem cells could be differentiated into insulin - producing pancreatic cells which are transplanted into the patients body
34
where would you source the stem cells for treating type 1 diabetes
stem cell donors or therapeutic cloning
35
where would you source the stem cells needed for treating paralysis
stem cell donors or therapeutic cloning
36
what is paralysis
damage to cells in the spinal cord, preventing signals from the brain reaching muscles in parts of the body resulting in loss of movement
37
how could stem cells treat paralysis
stem cells could be differentiated into nerve cells which are transplanted into the damaged region of the nervous system
38
what is therapeutic cloning
where:
- an embryo is produced with the same genes as the patient
- a 5-day embryo is the best source for embryonic stem cells
- stem cells from embryos created in this way are not rejected by the patients body which means they don't have to take drugs to suppress their immune system
39
what is therapeutic cloning
where:
- an embryo is produced with the same genes as the patient
- a 5-day embryo is the best source for embryonic stem cells
- stem cells from embryos created in this way are not rejected by the patients body which means they don't have to take drugs to suppress their immune system
40
what are the benefits of using stem cells in medicine
- great potential to treat a variety of medical problems
- organs developed from their own stem cells are less likely to be rejected + no waiting for organ donation
- adult stem cells are already successfully used in treatments
41
what are the general risks and issues of using stem cells in medicine
- stem cells cultured in a lab could become injected and pass this on to patient
- risk of cultured stem cells growing out of control and developing into cancer cells
- low numbers of stem cell donors
42
what are the ethical and social issues of using stem cells in medicine
if using embryonic stem cells:
- harm/death to embryo
- embryo can't give consent
- should embryos even be treated with human rights
educating the public sufficiently about what stem cells can and cant be used for
embryonic cells may be sourced from unused IVF treatment - who gives permission
43
what is an enzyme
a biological catalyst for metabolic reactions
44
what stores does photosynthesis transfer energy from and to
from light energy to chemical energy
45
what is the structure of the human alimentary canal
mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreas
46
what is transpiration
the evaporation of water from the surface of a plant
47
what does urine contain
water, urea and ions
48
what is homeostasis
the maintenance of a constant internal environment
49
what are some examples of homeostasis
body water content
body temperature
50
what is a mutation
a rare, random change in genetic material that can be inherited
51
how can scientist ensure that vaccines contain harmless pathogens
- kill the pathogen
- make the pathogen unable to grow or divide
- use only fragments of pathogens
52
what is one example of fungi
mucor or yeast
53
what is a pathogenic example of a protoctist
- plasmodium causing malaria
54
what are two examples of protoctist and what features do they have
- amoeba that have features like and animal cell
- chlorella which are more like plants
55
what are examples of viruses in humans
- influenza causing flu
- HIV virus causing AIDS
56
what are the different ways a vaccine can be administered
- orally, nasally or via injection
57
how do vaccines work
- once in the bloodstream the antigens trigger an immune response:
- - the lymphocytes spot the antigens and produce specific antibodies
58
why do vaccinations cause long term immunity
- memory cells and antibodies remain circulating in the blood stream
- therefore when the antigen is encountered again the antibodies can be produced much faster and on a much larger scale
- due to the rapid nature of the response, the pathogen is unable to cause disease
59
what is the importance of vaccination
- they reduce the likelihood that an infected individual will spread the pathogen to others (HERD IMMUNITY)
- they reduce the cases of certain diseases and even eradicated diseases such as smallpox
- epidemics cane be prevented
60
what are the disadvantages of vaccinations
- pathogens can MUTATE so the antibodies no longer recognise the pathogen rendering the vaccination useless
- side-effects can reduce the uptake in the population
61
what do memory cells enable
- future antibody production to occur sooner, faster and in greater quantity
62
what IS a platelet
a fragment of a cell involved in blood clotting
63
how do platelets stop the bleeding when a person is cut
- when exposed to air a series of reactions occur
- the platelets release chemicals that cause the soluble fibrinogen to convert to insoluble fibrin
- to form an insoluble mesh across the wound,
- trapping the red blood cells
- and therefore causing a clot
- this clot eventually dries and develops into a scab
64
what does a scab do
- it stops the flow of blood outside the body
- prevents bacteria/microorganisms entering the wound
65
what is the importance of blood clotting
- prevents significant blood loss
- prevents the entry of microorganisms which could cause infection
- remains in place until new skin has grown underneath it, effectively providing a seal
66
what functions do the kidneys provide
- regulate the water content of the blood
- excrete toxic waste products of metabolism
(osmoregulation and excretion)
67
what are some substances that the kidney removes from the blood
- urea
- ammonia
- excess hormones
- excess salt/ions
- creatinine
- excess water
- uric acid
68
describe the structure of the urinary system
- two kidneys
- ureters
- bladder
- urethra
- to outside of body
+ renal artery and vein
69
where are nephrons located in the kidney
- they start in the cortex and loop down into the medulla
70
how does the urine get from the blood to the bladder
after it is forced out of the blood:
- the contents of the nephrons drain into the renal pelvis and the urine collects there
- before it flows into the ureter
- to be carried to the bladder for storage
71
what is the structure of a nephron
- bowman's capsule
- proximal convoluted tubule
- loop of Henlé
- distal convoluted tubule
- collecting duct
surrounding this is a network of capillaries with a knotted section within the Bowman's capsule
72
what are the processes of the filtering of blood in the kidney
- Ultrafiltration
- selective reabsorption of glucose
- reabsorption of water and salts
73
what substances are filtered out during ultrafiltration and what is this called
- glucose
- urea
- water
- used hormones
- salts
glomerular filtrate
74
where is water reabsorbed
loop of henle and collecting duct
75
where are salts reabsorbed
loop of henle
76
where is glucose reabsorbed
proximal convoluted tubule
77
composition of urine
- water
- urea
- ions
78
how is the nephron adapted for the reabsorption of glucose
they contain many mitochondria for active transport
79
why can glucose only be reabsorbed in one place in the nephron
because the gates that facilitate active transport are only found in the proximal convoluted tubule
80
why do doctors check your urine to see if you have diabetes
because those with diabetes cannot ocntrol their blood sugar level so they are often very high
this mean not all of the glucose can be reabsorbed using active transport so much of it continues in the filtrate and ends up as urine
81
what is another word for bursting of cells
lysis
82
what is an isotonic solution
when the water potential is equal between the blood cell and the solution
83
describe the structure of a DNA molecule
two strands coiled to form a double helix, the strands being linked by a series of unpaired bases: adenine-thymine (AT) and guanine-cytosine (GC)
84
how is the structure of an RNA molecule different to DNA
the thymine is replaced by uracil
it is single stranded instead of double
85
what are some examples of RNA molecules
messenger RNA
transfer RNA
ribosomal RNA
86
what is a gene
a stand of DNA that codes for a protein
87
what are the processes of protein synthesis
- transcription -> DNA is transcribed and an mRNA molecule is produced
- translation -> mRNA is translated and an amino acid sequence is produced
88
why is mRNA needed
because DNA must remain in the nucleus so a copy (mRNA) is made to move it to the ribosomes in the cytoplasm
89
what are the steps of transcription
- the two strands of DNA are unzipped (using the enzyme helicase) by breaking the weak hydrogen bonds between the base pairs
- free RNA molecules are attracted to the exposed DNA by complimentary base pairing
- RNA polymerase catalyses the formation of covalent bonds between these bases to form mRNA
- the mRNA then leaves the nucleus
90
what are the steps of translation
- the mRNA attaches to a ribosome
- the tRNA moleculesbind to their specific amino acids
- the anticodons on each tRNA pair with the codons on the mRNA molecule
- two tRNA molecules attach at one time and a peptide bond is formed between the two amino acids
- this process continues until a stop codon on the mRNA is reached
- the amino acid chain folds into the correct shape to form a protein
91
what is the structure of a tRNA
- a triplet of unpaired bases at one end (anticodon)
- a region where the specific amino acid can attach at the other
