Ch4-P120-129 Flashcards Preview

BMS129-A&P > Ch4-P120-129 > Flashcards

Flashcards in Ch4-P120-129 Deck (20):
1

kineto = ; chore = 

= motion; = place

2

poly = ; morph =

multiple, form

3

A gene can be defined as?

 an information-containing segment of DNA that codes for the production of a molecule of RNA, which in most cases goes on to play a role in the synthesis of one or more proteins.

4

The genome is?

all the DNA in a human or organism

5

The body can make millions of different proteins, all from the same ____ amino acids, and encoded by genes made of just  four nucleotides __, __, __, __

  • 20
  •  A, T, C, G

6

The genetic code is

a system that enables these four nucleotides (A, T, C, G) to code for the amino acid sequence of all proteins

7

The minimum code to symbolize 20 amino acids is

 three nucleotides per amino acid

8

 The body can make millions of different proteins, all from the same __ amino acids and all encoded by genes made of just __ nucleotides labelled (_, _, _, _).

 20

4

A, T, C, G

9

A base triplet is

a sequence of 3 DNA nucleotides that stands for 1 amino acid. It is found on DNA molecule.

When messenger RNA is produced, it carries a coded message based on these DNA triplets.

10

Codon is

  • a “mirror-image” sequence of nucleotides found in mRNA
  • 64 possible codons (43)
  • often 2-3 codons represent the same amino acid
  • start codon = AUG (also codes for methionine)
  • 3 stop codons (signal end of message) = UAG, UGA, UAA

A codon is a 3-base sequence in mRNA

11

  1. The genetic code in DNA specifies which ____ a cell can make.
  2. All the body's cells except the sex cells and some immune cells contain ______ genes.
  3. However, different genes are activated in _____ cells; for example, the genes for digestive enzymes are active in stomach cells but not in muscle cells.
  4. Any given cell uses only ____ to _____ of its genes; the rest remain dormant in that cell, but may be functional in other types of cells.

  1. proteins
  2. identical
  3. different
  4. one-third to two-thirds 

12

messenger RNA is?

The form of RNA that mediates the transfer of genetic information from the cell nucleus to ribosomes in the cytoplasm, where it serves as a template for protein synthesis. It is synthesized from a DNA template during the process of transcription.

When a gene is activated, a messenger RNA (mRNA) is made—a mirror image of the gene, more or less.

13

Explain transcription and translation (text explanation)

Most mRNA migrates from the nucleus to the cytoplasm, where it serves as a code for assembling amino acids in the right order to make a particular protein. In summary, you can think of the process of protein synthesis as DNA → mRNA → protein, with each arrow reading as “codes for the production of.” The step from DNA to mRNA is called  transcription, and the step from mRNA to protein is called translation. Transcription occurs in the nucleus, where the DNA is. Most translation occurs in the cytoplasm, but 10% to 15% of proteins are synthesized in the nucleus, with both steps occurring there.

14

Transcription is?

  • when messenger RNA (mRNA) is formed next to an activated gene
  • mRNA migrates to cytoplasm

15

Explain in transcription how instructions are copied from DNA to RNA

  • RNA polymerase binds to DNA
    • at site selected by chemical messengers from cytoplasm
  • opens DNA helix and transcribes bases from 1 strand of DNA into pre-mRNA
    • if C on DNA,  G is added to mRNA
    • if A on DNA,  U is added to mRNA, etc.
  • rewinds DNA helix 

16

Steps in Translation of mRNA

Converts alphabet of nucleotides into a sequence of amino acids to create a specific protein

  • Ribosome in cytosol or on rough ER
    • small subunit attaches to mRNA leader sequence
    • large subunit joins and pulls mRNA along as it “reads” it
      • start codon (AUG) where protein synthesis begins
    • small subunit binds activated tRNA with corresponding anticodon
    • large subunit enzyme forms peptide bond
  • Growth of polypeptide chain
    • next codon read, next tRNA attached, amino acids joined, first tRNA released, process repeats and repeats
  • Stop codon reached and process halted
    • polypeptide released and ribosome dissociates into 2 subunits

17

Transfer RNA (tRNA) is

a small molecule in cells that carries amino acids to organelles called ribosomes, where they are linked into proteins.

  • Activation by ATP binds specific amino acid and provides necessary energy to join amino acid to growing protein molecule
  • Anticodon binds to complementary codon of mRNA

An anticodonis a unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA.

18

muta =

change

19

Law of complementary base pairing in DNA allows the

 building of one DNA strand based on the bases in 2nd strand. It shows that we can predict the base sequence of one DNA strand if we know the sequence of the other. 

20

Semiconservative replication is?

each new DNA molecule contains one new helix and one conserved from parent DNA