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Cell Structure Flashcards

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1
Q

what do cells do in order to become specialised

A

differentiation

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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

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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

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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

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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

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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

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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
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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
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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
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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
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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
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12
Q

what are some examples of specialised cells in animals

A

ciliated
nerve
egg
sperm
red blood

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13
Q

what are some examples of specialised cells in plants

A

root hair cell
xylem vessel
palisade mesophll cell

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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
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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
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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
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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

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18
Q

what are the three types of stem cell

A

embryonic
adult
meristem

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19
Q

where are embryonic stem cells found

A

on the inside layer of an embryo

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20
Q

where are adult stem cells found

A

bone marrow
skin
umbilical cord blood
other organs such as liver and brain

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21
Q

what is similar about embryonic and meristem cells

A

they are both undifferentiated and unspecialised

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22
Q

why are adult stem cells not entirely useful

A

they have a limited ability to differentiate

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23
Q

what cells can be produced from an embryonic stem cell

A

all the types of specialised cell found in the body

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24
Q

what cells can be produced from an adult stem cell found in the skin

A

skin cells and hair follicles

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25
Q

what cells can be produced from meristem cells

A

one cell has the ability to produce a whole new plant

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26
Q

where are meristem cells found

A

in the tips of roots and shoots (the growing regions of plants)

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27
Q

what cells can be produced from an adult stem cell found in the bone marrow

A

mainly blood cells (red blood cells, cells of the immune system)

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28
Q

what cells can be produced from an adult stem cell found in the umbilical cord blood

A

cells of the blood (red and white), muscle and nerve tissue

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29
Q

what cells can be produced from an adult stem cell found in other organs such as the liver and brain

A

cells found in these organs

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30
Q

what does the term totipotent mean

A

they can form all of the different tissues and organ needed during development

embryonic stem cells are totipotent

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31
Q

what is the main role of adult stem cells

A

to replace cells lost through damage or to produce new cells for growth

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32
Q

what is type 1 diabetes

A

inability of the pancreas to produce insulin to control blood sugar levels

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33
Q

how can stem cells treat type 1 diabetes

A

stem cells could be differentiated into insulin - producing pancreatic cells which are transplanted into the patients body

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34
Q

where would you source the stem cells for treating type 1 diabetes

A

stem cell donors or therapeutic cloning

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35
Q

where would you source the stem cells needed for treating paralysis

A

stem cell donors or therapeutic cloning

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36
Q

what is paralysis

A

damage to cells in the spinal cord, preventing signals from the brain reaching muscles in parts of the body resulting in loss of movement

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37
Q

how could stem cells treat paralysis

A

stem cells could be differentiated into nerve cells which are transplanted into the damaged region of the nervous system

38
Q

what is therapeutic cloning

A

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
Q

what is therapeutic cloning

A

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
Q

what are the benefits of using stem cells in medicine

A
  • 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
Q

what are the general risks and issues of using stem cells in medicine

A
  • 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
Q

what are the ethical and social issues of using stem cells in medicine

A

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
Q

what is an enzyme

A

a biological catalyst for metabolic reactions

44
Q

what stores does photosynthesis transfer energy from and to

A

from light energy to chemical energy

45
Q

what is the structure of the human alimentary canal

A

mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreas

46
Q

what is transpiration

A

the evaporation of water from the surface of a plant

47
Q

what does urine contain

A

water, urea and ions

48
Q

what is homeostasis

A

the maintenance of a constant internal environment

49
Q

what are some examples of homeostasis

A

body water content
body temperature

50
Q

what is a mutation

A

a rare, random change in genetic material that can be inherited

51
Q

how can scientist ensure that vaccines contain harmless pathogens

A
  • kill the pathogen
  • make the pathogen unable to grow or divide
  • use only fragments of pathogens
52
Q

what is one example of fungi

A

mucor or yeast

53
Q

what is a pathogenic example of a protoctist

A
  • plasmodium causing malaria
54
Q

what are two examples of protoctist and what features do they have

A
  • amoeba that have features like and animal cell
  • chlorella which are more like plants
55
Q

what are examples of viruses in humans

A
  • influenza causing flu
  • HIV virus causing AIDS
56
Q

what are the different ways a vaccine can be administered

A
  • orally, nasally or via injection
57
Q

how do vaccines work

A
  • once in the bloodstream the antigens trigger an immune response:
    • the lymphocytes spot the antigens and produce specific antibodies
58
Q

why do vaccinations cause long term immunity

A
  • 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
Q

what is the importance of vaccination

A
  • 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
Q

what are the disadvantages of vaccinations

A
  • 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
Q

what do memory cells enable

A
  • future antibody production to occur sooner, faster and in greater quantity
62
Q

what IS a platelet

A

a fragment of a cell involved in blood clotting

63
Q

how do platelets stop the bleeding when a person is cut

A
  • 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
Q

what does a scab do

A
  • it stops the flow of blood outside the body
  • prevents bacteria/microorganisms entering the wound
65
Q

what is the importance of blood clotting

A
  • 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
Q

what functions do the kidneys provide

A
  • regulate the water content of the blood
  • excrete toxic waste products of metabolism

(osmoregulation and excretion)

67
Q

what are some substances that the kidney removes from the blood

A
  • urea
  • ammonia
  • excess hormones
  • excess salt/ions
  • creatinine
  • excess water
  • uric acid
68
Q

describe the structure of the urinary system

A
  • two kidneys
  • ureters
  • bladder
  • urethra
  • to outside of body

+ renal artery and vein

69
Q

where are nephrons located in the kidney

A
  • they start in the cortex and loop down into the medulla
70
Q

how does the urine get from the blood to the bladder

A

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
Q

what is the structure of a nephron

A
  • 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
Q

what are the processes of the filtering of blood in the kidney

A
  • Ultrafiltration
  • selective reabsorption of glucose
  • reabsorption of water and salts
73
Q

what substances are filtered out during ultrafiltration and what is this called

A
  • glucose
  • urea
  • water
  • used hormones
  • salts

glomerular filtrate

74
Q

where is water reabsorbed

A

loop of henle and collecting duct

75
Q

where are salts reabsorbed

A

loop of henle

76
Q

where is glucose reabsorbed

A

proximal convoluted tubule

77
Q

composition of urine

A
  • water
  • urea
  • ions
78
Q

how is the nephron adapted for the reabsorption of glucose

A

they contain many mitochondria for active transport

79
Q

why can glucose only be reabsorbed in one place in the nephron

A

because the gates that facilitate active transport are only found in the proximal convoluted tubule

80
Q

why do doctors check your urine to see if you have diabetes

A

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
Q

what is another word for bursting of cells

A

lysis

82
Q

what is an isotonic solution

A

when the water potential is equal between the blood cell and the solution

83
Q

describe the structure of a DNA molecule

A

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
Q

how is the structure of an RNA molecule different to DNA

A

the thymine is replaced by uracil

it is single stranded instead of double

85
Q

what are some examples of RNA molecules

A

messenger RNA
transfer RNA
ribosomal RNA

86
Q

what is a gene

A

a stand of DNA that codes for a protein

87
Q

what are the processes of protein synthesis

A
  • transcription -> DNA is transcribed and an mRNA molecule is produced
  • translation -> mRNA is translated and an amino acid sequence is produced
88
Q

why is mRNA needed

A

because DNA must remain in the nucleus so a copy (mRNA) is made to move it to the ribosomes in the cytoplasm

89
Q

what are the steps of transcription

A
  • 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
Q

what are the steps of translation

A
  • 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
Q

what is the structure of a tRNA

A
  • a triplet of unpaired bases at one end (anticodon)
  • a region where the specific amino acid can attach at the other

Biology (22 decks)

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