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Y11 Human Bio ATAR > DNA and Reproduction > Flashcards

DNA and Reproduction Flashcards

1
Q

Nuclear DNA in terms of location and quantities

A

located within the nucleus of eukaryote cell. enough to stretch from here to the moon 6,000

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2
Q

Nuclear DNA in terms of structure

A

large and complex
tightly coiled
sugar phosphate backbone - made of deoxyribo sugar backbone
Nitrogenous bases - Adenine, cytosine, thymine, guanine
Bonded by hydrogen

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3
Q

Explain the role of histones

A

histones are proteins which DNA is tightly coiled around many times
Histones serve to both package and organize DNA within the nucleus.

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4
Q

Compare DNA, chromatin, chromosome & genes

A

DNA -> Deoxyribonucleic acid
Chromatin -> consists of the unraveled condensed structure of DNA for the purpose of packaging into the nucleus
Chromosome -> consists of the highest condensed structure of DNA (having genes)
Genes -> short sections of DNA responsible for characteristics like eye color or blood group.

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5
Q

What are the matching base pairs

A

Adenine - Thymine (two hydrogen bonds)

Cytosine - Guanine (Three hydrogen bonds)

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6
Q

describe the relationship between DNA, base pairs, codons amino acids and proteins

A

DNA -> made up of deoxyribosugar backbone with nitrogenous base pairs
Base pairs -> three base pairs code for a codon
Codons -> code for amino acids and stop codon
amino acids -> code for proteins,

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7
Q

Describe RNA

A

Ribonucleic acid. no deoxyribose
single stranded
uracil pairs with adenine instead of thymine in RNA
three types; mRNA, tRNA, ribosomal RNA

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8
Q

Compare RNA and DNA

A

DNA -> Double stranded whereas RNA-> single stranded
DNA -> Deoxyribose sugar whereas RNA-> Ribonucleic acid
DNA-> nitrogenous bases are A,C,G,T whereas RNA -> A,C,G,U (uracil)
Function of DNA -> contains instructions for cell reproduction
Function of RNA -> mRNA, tRNA, rRNA

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9
Q

What are the different types of RNA

A

mRNA (messenger RNA)
tRNA (transfer RNA)
rRNA (ribosomal RNA)

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10
Q

describe mRNA

A

1) Travels from the nucleus to the cytoplasm with the instructions for making proteins
- ‘messenger’ between the DNA in the nucleus and the ribosomes in the cytoplasm
2) Instructions are carried in the form of codon (Codon - 3 Nitrogenous Bases)
3) The first codon is called the “start” codon (AUG) - this is when the mRNA will attach to the ribosome
- This tells the ribosomes where the protein-building instructions begin
4) The rest of the molecule is a sequence of nucleotides that dictates the sequence of amino acids for the particular protein that is being made
The last codon is called the “stop” codon (UAG)

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11
Q

tRNA

A

1) Each transfer RNA has an anticodon at one end and an amino acid binding site at the other end
- The bases composing the anticodon are complementary to mRNA codons
2) Transfer RNA reads the message carried by mRNA and gathers the amino acids for making the protein
3) Transfer RNA transfers amino acids from the cytoplasmic pool of amino acids to a ribosome
4) A cell keeps its cytoplasm stocked with all 20 amino acids
One end of the tRNA attached to one amino acid and carries it to the ribosome

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12
Q

rRNA

A
  • Found in the ribosome
    These are used to bind the mRNA and tRNA to the ribosome. This allows all components required for the synthesis of the proteins to be held together
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13
Q

basic overview of protein production. i.e Transcription

A

Transcription -> the process of forming a strand of RNA from a strand of DNA
occurs in nucleus
The start codon PROMOTER is where RNA polymerase attaches and initiates transcription
The stop codon TERMINATOR signals the end of transcription

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14
Q

basic overview of protein production. i.e Translation

A

Occurs in ribosome
Translation is the process that takes the information passed from DNA as messenger RNA and turns it into a series of amino acids bound together with peptide bonds.

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15
Q

Steps of transcription

A

RNA polymerase binds to a site on the DNA molecule called the promoter
RNA polymerase separates the DNA strands
One strand of DNA is used as a template
New nucleotides are inserted according to the base pairing rules
When transcribing RNA, adenine pairs with uracil
Cytosine pairs with Guanine
This continues until the terminator is reached
As the RNA polymerase moves along the DNA molecule, hydrogen bonds between the two strands of DNA are reformed
A single stranded RNA molecule has been transcribed
Exon & intron
Introns are cut out and removed
Remaining exons are spiced together to form mRNA

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16
Q

Steps of Translation

A

In the nucleus, DNA transcribes RNA
The RNA is sent to the cytoplasm in the form of mRNA
The mRNA attaches to a ribosome
As each codon of the mRNA molecule moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA. The amino acids are lined up in the right order on the ribosome
The ribosome hitches the amino acids together with peptide bonds and polypeptides are made. Remember, a polypeptide is a long chain of amino acids but is not a functioning protein. Polypeptides are sent to the ER and the Golgi apparatus where they are modified and shaped into functioning proteins

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17
Q

Where does transcription occur in the cell

A

Nucleus

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18
Q

Explain how mRNA is formed

A

introns must be sliced out of RNA

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19
Q

Role of helicase

A

unzips the dna by breaking the hydrogen bonds between the nitrogenous bases

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20
Q

Role of RNA polymerase

A

responsible for copying a DNA sequence into an RNA sequence

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21
Q

What is RNA editing, including exons and introns

A

RNA editing can be defined as a molecular process by which protein coding gene changes its message.
Introns are removed from the mRNA, whereas the extrons are used to express and encode proteins.

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22
Q

describe epigenetics in relation to gene expression and inheritance

A

Epigenetics is the altering of gene expression without changing the DNA base sequence.

Gene expression is through acetylation and methylation.

23
Q

Effect of DNA acetylation and methylation on gene expression

A

Gene expression is called acetylation and methylation.
Acetylation; - addition of acetyl group to a histone
- enhances/increases gene expression, as DNA unwinds and histones move apart making the dna more accessible
Methylation; - addition of methyl group to cytosine base in the DNA molecules
- inhibits/ reduces gene expression

24
Q

Describe the purpose of mitosis

A

The purpose of mitosis is to create two identical daughter cells from one parent cell

25
Q

Describe the location of mitosis

A

mitosis occurs in somatic cells, causing one cell to become two.

26
Q

Describe the number of chromosomes in MITOSIS

A

46

27
Q

How many daughter cells are produced by mitosis

A

2

28
Q

Prophase

A

P -> Prophase

  • Chromatin condenses and chromatids become visible as pair of chromosomes
  • Nucleoli dissappears as nuclear membrane breaks down
  • centrioles migrate to opposite poles of cell
  • spindle forms
29
Q

Metaphase

A

M -> Metaphase

- chromosomes line up at the equator of the cell and become attached to the spindle fibers

30
Q

Anaphase

A

A -> Anaphase

  • chromosomes divide at centromere
  • daughter chromatids move to opposite ends of spindle
31
Q

Telophase

A

T -> Telophase

  • Spindle disappears
  • nucleoli and nuclear membranes reform
  • centrioles divide into each daughter cell
  • chromosomes uncoil and disappear (turn back into chromatin)
  • cytokinesis begins
32
Q

Cell specialization

A

Cell specialization can be defined as the specializations of cells to serve a specific function.

33
Q

where does DNA replication occur

A

Nuclei of eukaryotic cells

34
Q

how does DNA replication occur

A

A representative portion of DNA, which is about to undergo replication.
The two strands of the DNA separate, the weak hydrogen bonds between the bases break
Free nucleotide are attracted to their complimentary bases

35
Q

role of helicase

A

unzips the dna

36
Q

role of helicase

A

unzips the dna

37
Q

role of DNA polymerase

A

replicated DNA molecules to build a new strand of DNA

38
Q

role of primase

A

makes the primer which lets DNA polymerase know where it needs to start its work.

39
Q

Role of ligase

A

helps glue DNA fragments together

40
Q

compare autosomes and sex chromosomes

A

Autosomes -> all the chromosomes in a cell other than sex chromosomes. -> homologous
Sex chromosomes -> the chromosomes that determine the sex of an individual
Male -> XY
Female -> XX

41
Q

the purpose of meiosis is;

A

is to form gametes that combine in sexual reproduction

41
Q

the purpose of meiosis is;

A

is to form gametes that combine in sexual reproduction

42
Q

Meiosis occurs in;

A

the sex organs of sexually reproducing organisms

43
Q

number of chromosomes in meiosis;

A

only have 23 chromosomes - haploid

44
Q

daughter cells produced in meiosis

A

4 haploid cells

45
Q

Stages of meiosis overview

A

P.M.A.T x2

46
Q

Prophase 1 of meiosis

A
  • DNA coils and individual chromosomes become visible

- genetic material is exchanged between chromosomes during crossing over

47
Q

crossing over

A

sharing of genetic material between non-sister chromatids in a homologous pair

48
Q

Metaphase 1 in meiosis

A
  • Each pair of recombined homologous chromosomes line up along the equator of the cell
  • either homologue may orientate towards either pole
49
Q

Anaphase 1 in meiosis

A
  • spindle fibres pull one chromosome from each homo pair towards opposite poles of the cell
  • each pole ends up with one copy of each chromosome
  • the cell now has half the number of chromosomes
50
Q

Telophase 1 and prophase 2 in meiosis

A

telophase 1 - the nuclear membrane reforms

Prophase 2 - spindle fibres form and attach to each of the chromatids

51
Q

M 2 and A 2 in meiosis

A

M2 - the chromosomes line up along the equator of the cell.

A2 - the spindle fibres contract and pull on chromatid from each chromosome to opposite ends of the cell

52
Q

telophase 2 in meiosis

A

the cell divides through forming 4 nuclei each with half the number of chromosomes as the parent cell

Y11 Human Bio ATAR (11 decks)

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