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Flashcards in MCBG Deck (173)
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1

Difference between nucleotide and nucleoside?

Nucleotide is phosphate + base + sugar
Nucleoside is base + sugar

2

Describe processes of PMAT

Prophase - chromosomes condense and spindles appear
Prometaphase - spindles attach to chromosomes
Metaphase - chromosomes line up
Anaphase- sister chromatids separate
Telophase- nuclear membrane reforms, chromosomes decondense
+ Cytokinesis - cytoplasm divides

3

Difference between centrosomes and centromeres?

Centromeres join sister chromatids in a chromosome and centrosomes are what mitotic spindles are attached to at the poles of the cell

4

What is chromosome condensation?

During DNA replication DNA is stored as chromatin but during mitosis it condenses to become chromosomes

5

What is a telomere?

Repeated sequence at the end of chromatids (e.g. TTAGGG) that will protect it from damage like the caps at the end of shoelaces

6

When do crossing over and random assortment occur?

Crossing over in prophase I, random assortment is metaphase I

7

What is karyotyping?

Number and appearance of chromosomes

8

What is mitotic nondisjunction?

Where a chromosome doesn't split into sister chromatids and get pulled to separate poles, so it results in aneuploidy (cell with more or less than 46 chromosomes)

9

What is mosaicism?

Presence of cells with different number of chromosomes than other cells in same body

10

Roughly describe meiosis

Meiosis I - diploid cell divides into 2 haploid cells
Meiosis II - 2 haploid cells become 4 haploid cells (essentially mitosis)

11

What is the official name for "jumping genes"?

Transposable element (transposons)- can change their place in the genome, sometimes to create or fix mutations

12

Which direction is mRNA synthesised?

5' to 3'

13

Which direction is DNA read?

3' to 5'

14

What are histones?

DNA is wrapped around histones to make a nucleosome (the structural unit of chromatin)

15

RNA polymerase

Poly A tail and cap

16

Types of RNA?

messenger, transfer, and ribosome

17

What is splicing?

Introns are removed from preRNA but exons stay, forming an mRNA (still with poly A tail and cap)

18

What happens after splicing?

mRNA leaves through nuclear pore

19

What does tRNA do?

Each tRNA attaches to one amino acid in the cytoplasm
amino acyl tRNA synthetase attaches a tRNA to an amino acid. Then a ribosome (rRNA) will join together the tRNA:amino acid with mRNA

20

Where does ribosome attach?

Ribosome attaches to cap region of mRNA moving towards the polyA tail

21

What are the EPA sites of a ribosome?

A is attachment, E is exit; ribosome moves towards the polyA tail. If

22

What are codons and anticodons?

3 nucleotides on mRNA are codons and 3 nucleotides of tRNA are anticodons

23

What are the EPA sites of a ribosome?

A is attachment, P is polypeptide, E is exit; ribosome moves towards the polyA tail. If a tRNA matches the codon the ribosome is on it will attach at A site

24

What are codons and anticodons?

3 nucleotides on mRNA are codons and 3 nucleotides of tRNA are anticodons

25

Where does RNA polymerase bind?

Binds to mRNA at the TATA box (signals where transcription should begin)

26

Describe the rough processes involved in making proteins

DNA replication in nucleus, then transcription where DNA is converted into pre-mRNA then splicing to remove introns then mRNA formed (transcription), then mRNA exits the nucleus and tRNA with amino acid joins and ribosome makes it happen, makes a chain of amino acids.

27

What is the wobble position?

5' base of anticodon and 3' base of codon where more than one codon can be recognised

28

What enzyme joins tRNA with its amino acid?

Aminoacyl tRNA synthatase

29

Tell me about formation of rRNA and its structure

Made in the nucleolus, 2 subunits (one large one small), formation with RNA polymerase I

30

How is translation terminated?

With stop codons e.g. UAA, UGA, UAG