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Biology > Cell Division > Flashcards

Cell Division Flashcards

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AP® Biology flashcards Biology 101 flashcards
0
Q

Chromosomes carry

A

Many Genes that control characteristics of the body

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1
Q

Every nucleus contains

A

Chromosomes

Coded instructions for the preside assembly of amino acids into all the proteins a cell needs

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2
Q

Different forms go genes are called

A

Alleles which may produce different characteristics

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3
Q

In body cells chromosomes are usually found in…

A

Pairs

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4
Q

Body cells divide by..

A

Mitosis to produce additional cells during growth or replacement cells

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5
Q

Mitosis

A

Chromosomes line up
Chromosomes pulled apart so copies of genetic material made
Cell divides once to form two genetically identical cells
Chromosomes are then copied

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6
Q

Meiosis

A

Cell division for gamete/ sex cell production
Halves chromosome number (ie: 46->23)
4 chromosomes (2pairs), separates the pairs in first division
Then in the second division the chromosome copies are pulled apart like in mitosis

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7
Q

DNA

A

Carries coded instructions for assembling amino acids in precise sequences to make proteins
Replicate itself so after every cell division all cells carry exactly the same genes

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8
Q

Chromosome numbers in the human body

A

23 pairs–>46 in total
One pair determines sex (female: XX, male: XY)
Each chromosome is one DNA molecule about 5-7 cm long with a copy that is also 5/7cm long
DNA strands fold into coils that are held together in the middle by the centromere

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9
Q

Human life cycle

A 
Each female and male gamete has 23 unpaired chromosomes
Fertilisation: gamete fusion to make a zygote with 23 paired chromosomes
Mitosis
Ball of undifferentiated cells
Mitosis and differentiation 
Foetus
Birth 
Puberty
Testes/ovary germ cells
Meiosis halves the chromosome numbers
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10
Q

Structure of DNA

A

James Watson/ Francis Crick
DNA= polymer made up of monomers called nucleotides.
Each nucleotide has 3 components:
Protein
Sugar
Base
4 different types of bases, means 4 different nucleotides to build DNA from
DNA is 2 long stands of nucleotides lying side by side, held together by weak bonds between base pairs & in double helix

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11
Q

DNA Replication

A
  1. An enzyme moves along the double helix breaking bonds and separating two strands
  2. Each separate strand acts as a template for building a new strand
  3. New strands are assembled along the original 2 strands
  4. This process continues as the enzyme unwinds more helix
    These two identical double strands of DNA are twisted into double helix the held together by centromeres
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12
Q

How does DNA control….

A

DNA strands contain sections called genes
Each gene has a specific sequence for making proteins
Each base triplet contains codes for one amino acid
They are then aligned precisely in the right order
Then folds into a different shape which determines function

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13
Q

Alleles

A

The alternative form of the gene

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14
Q

CAPITAL LETTERS FOR GENES

A

Dominant allele

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15
Q

lower case letters for alleles

A

Recessive alleles

16
Q

Homozygous dominant

A

GG

17
Q

Homozygous recessive

A

gg

18
Q

Heterozygous

A

Gg

19
Q

Phenotype=

A

(Feature/characteristic)= genotype + environment

(Combination of specific alleles)

20
Q

2 types of variation

A

Continuous

Discontinuous

21
Q

Continuos variation

A

Phenotype feature varies across a range of values between two extremes
Often caused by many gene interactions & the environment

22
Q

What are stem cells

A

Unspecialised cells which are found in human embryo and adult bone marrow

23
Q

Where do u find stem cells

A

1) . Embryo

2) . Adult bone marrow

24
Q

What does stem cells ‘differentiating’ mean?

A

When a stem cell changes into a type of body cell eg: nerve cell or muscle cell

25
Q

What could stem cells potentially do in the future

A

Therapeutic cloning so creating cells from stem cells eg nerve cells to cure paralysis. Has already been done with a trachea

26
Q

What is the name given the the set sequence a cell divides

A

Cell cycle- periods of active cell division followed by non-dividing phase.
In embryos & young active periods are more frequent
After puberty cell cycle slows down in most tissues (apart from skin, blood & digestive lining).

27
Q

Why might a cell change

A

Mutations in genetic material

28
Q

2 types of tumour

A

Benign

Malignant

29
Q

Benign tumour

A

Grows in one place

30
Q

Danger of benign tumour

A

Takes up space so could compress brain for example

31
Q

Malignant Tumour

A

Tumour that can spread round the body, invading healthy tissues as well as splitting and forming secondary tumours

32
Q

Dangers of malignant tumour

A

Cancer

Secondary tumours

33
Q

2 causes of cancer

A

Carcinogens: cancer causing chemicals

Ionising radiation: can cause cells to mutate eg: uv-light & x-rays

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