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Biology Units 1/2 > notes > Flashcards

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1
Q

Binary fission

A

The division of a cell into 2 without mitosis; the process by which a prokaryotic cell splits to form 2 daughter cells.

  • Similar to mitosis but occurs in prokaryotic cells as there is only one chromosome and no centromere.

Process includes:

  • DNA replication
  • Chromosome segregation
  • Cytokinesis
  • Produces 2 daughter cells with identical DNA to parent cell

Occurs in eukaryotic cells but only for producing:

  • Mitochondria
  • Chloroplasts
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2
Q

Apoptosis example

A

The death of cells which occurs as a normal and controlled part of an organism’s growth or development.

Example of Apoptosis :

  • Enables tadpole to lose its tail as it becomes a frog
  • Allows human embryo to lose the webbing between its fingers and toes
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3
Q

Failure in Apoptosis

A

Failure in Apoptosis can result in many problems, ranging from development defects to cancer

  • Formation of cancer happens when apoptosis is avoided and cells do not die as they should
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4
Q

Cell cycle checkpoints

A

G0 - resting state

  • Doesn’t divide or preparing for division
  • Occurs outside of cell cycle
  • Damaged cells are located here
G1 checkpoint 
Check for:
- Cell size 
- Nutrients 
- Growth factors 
- DNA damage

G2 checkpoint
Check for:
- Cell size
- DNA replication

Mitosis checkpoint - spindle assembly checkpoint
Check for:
- Chromosome attachment to spindle

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5
Q

Tumor suppressor genes

A
  • Inhibit cell division
  • Normal genes that slow down cell division
  • Repair DNA mistakes
  • Tell cells to when to die
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6
Q

Chemical mutagens

A
  • Ability to interfere with DNA

- Interrupts its structure, sequence and replication

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7
Q

Physical mutagens

A
  • Ultraviolet light, X rays and nuclear radiation
  • When UV light is absorbed DNA is damaged
  • Mutations in tumor suppressor gene p53 play a critical role in development of precancerous lesions and have been implicated in all types of skin cancer
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8
Q

Biological mutagens

A
  • Viruses - take over cells
  • Impair cell cycle regulation - results in cancer
  • Cause uncontrolled cell growth
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9
Q

Stem cells

A

Stem cells are undifferentiated cells that have the potential to replicate and to develop into many different kinds of cell

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10
Q

Stem cells ( Asexual reproduction)

A

Stem cells are undifferentiated cells that have the potential to replicate and to develop into many different kinds of cell

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11
Q

Totipotent stem cells ( Asexual reproduction)

A

Ability to form embryo and membranes that will surround, support and nourish it
Example = the early embryo before formation of inner cell mass

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12
Q

Pluripotent stem cells ( Asexual reproduction)

A

Capable of giving rise to most but not all tissues of an organism
Example = the inner cell mass

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13
Q

Multipotent stem cells ( Asexual reproduction)

A

Able to give rise to cells that have a specific function

Example = blood stem cells

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14
Q

Fission ( Asexual reproduction)

A
  • Single celled eukaryotic or prokaryotic organisms
  • Divide into 2 new organisms
  • Each is an exact copy of parent cell
  • Nucleus is replicated and cytoplasm splits to form 2 new daughter cells
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15
Q

Budding ( Asexual reproduction)

A
  • New organism is grown on the outside of the parent organism
  • Eventually detaches as its own complete organism
  • Hydra, yeast
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16
Q

Vegetable propagation ( Asexual reproduction)

A
  • Only in plants
  • Plants grow from cuttings
  • New plant forms through mitosis - genetically identical to parent plant
  • Plant grows - cells undergo differentiation and become specialised
  • Used for agricultural purposes to replicate qualities in plants
17
Q

Spore formation ( Asexual reproduction )

A
  • Spores are hardy self contained capsules - single celled structures
  • Contains exact copy of DNA of the parent
  • Can form an entire new organism in right conditions
    Spores can survive for hundreds of years and still germinate
  • Prokaryotes, fungi, plants
18
Q

Disadvantages of asexual reproduction in certain situations

A
  • Offspring are genetically identical
  • Parental care of offspring is limited or none
  • Large numbers of offspring may compete for limited resources
  • Lack of genetic diversity
19
Q

Nuclear transfer

A
  • Process made famous in 1996 - Dolly the sheep
  • Nucleus of adult sheep’s mammary cell taken and inserted into ovum - which has nucleus removed
  • Resulting blastocyst transferred to surrogate mother
    Method has very low success rate for live births

-

20
Q

Nuclear transfer ( Asexual reproduction )

A
  • Process made famous in 1996 - Dolly the sheep
  • Nucleus of adult sheep’s mammary cell taken and inserted into ovum - which has nucleus removed
  • Resulting blastocyst transferred to surrogate mother
    Method has very low success rate for live births

-

21
Q

Issues of cloning ( Asexual reproduction)

A

If we’re using adult cells and putting them into eggs to form blastocyst

  • Gamete cells - stem cells in embryo that allows offspring to survive.
  • Not successful as cells are different and the adult cells aren’t stem cells
  • Can’t use adult cells for cloning but you may be able to use adult stem cells instead
    It is failing because they aren’t using stem cells
22
Q

Multiple allele

A

Multiple allele are controlled by a single gene but many alleles.

23
Q

Polygenic inheritance

A

characteristic controlled by more than one gene is known as a polygenic characteristic.

24
Q

Continuous

A

When traits show a range of phenotypes they are called continuous variation whereas only one gene is involved and results in a small number of phenotypes called discontinuous variation.

25
Q

Pure Breeding

A

A line of organisms that always produce offspring with the same phenotype when crossed with each other.

26
Q

Nucleotides

A

The basic building block of nucleic acids (DNA and RNA), which are linked together by phosphodiester bonds; each nucleotide is made up of a five carbon sugar, a phosphate group and a nitrogenous base

27
Q

Nucleotide base pairs

A

Two complementary nucleotide bases that are joined together by hydrogen bonding in a DNA double strand

28
Q

Autosome

A

A chromosome that is the same in both males and females of a species, autosomes do not include sex chromosomes

29
Q

Nitrogenous base

A

A structural component of nucleotides, DNA has adenine (A), cytosine (C), guanine (G) and thymine (T), in RNA thymine is replaced with uracil (U).

30
Q

Monoploidy

A

An individual that contains one half the normal number of chromosomes is a monoploid and exhibits monoploidy. Monoploids are very rare in nature because recessive lethal mutations become unmasked, and thus they die before they are detected.

31
Q

Polyploidy

A

When a cell or organism has a genome compromising three or more copies of each chromosomes, represented by 3n, 4n, 5n, 6n etc. (more than two paired homologous pairs)

32
Q

Aneuploidy

A

Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46.

33
Q

Trisomy 21 (Down syndrome)

A

The condition in which is caused by an extra copy of chromosome number 21.

34
Q

Klinefelter’s syndrome (XXY syndrome)

A

A genetic condition in which a male is born with an extra copy of the X chromosome

Biology Units 1/2 (5 decks)

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