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GAMSAT D > Section 3 - Biology > Flashcards

Section 3 - Biology Flashcards

1
Q

Cytoplasm

A

The interior of the cell. It refers to all cell components enclosed by the cell’s membrane.

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2
Q

Cytosol

A

The solution which bathes the organelles and contains numerous solutes like amino acids, sugars, proteins, etc.

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3
Q

Cytoskeleton

A

Extends throughout the entire cell and has importance in the shape and intracellular transportation

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4
Q

Microfilaments

A

Important for cell movement and contraction

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5
Q

Flagellum

A

Organelle of locomotion found in sperm and bacteria

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6
Q

Mitochondria

A

Membrane-bound organelle. The powerhouse. Produce energy for the cell through aerobic respiration.

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7
Q

Lysosomes

A

Membrane-bound organelles. Suicide cells.

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8
Q

Endoplasmic Reticulum

A

Membrane-bound organelle. Synthesis centre. - RER = protein synthesis - SER = lipid transport and synthesis

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9
Q

Golgi Apparatus

A

Membrane-bound organelle. The export department. Involved in protein modifications and it also packages secretory proteins in membrane-bound vesicles which can be exocytosed

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10
Q

Peroxisomes

A

Membrane-bound organelle. Contain enzymes whose functions include oxidation of long-chain fatty acids and synthesis of cholesterol.

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11
Q

Nucleus

A

Membrane-bound organelle. Surrounded by a double membrane, the nuclear envelope. There are nuclear pores which allow transportation. Protein synthesis. Nucleolus - DNA found here.

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12
Q

DNA 1. What is DNA made up of? 2. What is the DNA double helix composed of and what bonds connect it? 3. What type of replication does DNA do? 4 Where do the phosphodiester bonds form between? 4. What stage of the Cell cycle is DNA synthesised?

A
  1. DNA is made up of nucleotide subunits, which polymerize via phosphodiester bonds to form a nucleic acid. A nucleotide is composed of a 5-carbon sugar, a nitrogen base and an inorganic phosphate. - Sugar in DNA = Deoxyribose, Sugar in RNA = Ribose - Purines = 2 rings, A, G - Pyridamines = 1 ring, C, T, U 2. Two complementary and anti-parallel DNA strands held together by hydrogen bonds 3. Semi-conservative: each strand of the double helix can serve as a template to generate the complementary strand. And semi-discontinuous. 4. Phosphodiester bonds form between a free 3’ hydroxyl group and a free 5’ phosphate group. 5. DNA is Synthesised in the S phase.
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13
Q

Mitosis

  • Interphase (G1, S, G2)
  • Mitosis (prophase, metaphase, anaphase, telophase)
  • Cytokinesis
A

Interphase

  • G1 = cell prepares for DNA synthesis
  • S = synthesis of DNA
  • G2 = begins preparing for mitosis

Mitosis

  • Prophase - pairs of centrioles migrate away from each other while microtubules appear in between forming a spindle. Chromatin condenses into visible chromosomes. Kinetochores develop in the centromere region. Nuclear envelope disappears.
  • Metaphase - centromeres line up along equator. Microtubules, from the spindle, attach to the kinetochores.
  • Anaphase - sister chromatids are pulled apart to opposite poles. A cleavage furrow forms around the cell.
  • Telophase - new membrane form around the daughter nuclei. Cleavage furrow becomes deepened.
  • Cytokinesis - cell separation.
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14
Q

Viruses & their life cycles

A
  • The genetic material for viruses may be either DNA or RNA but not both
  • They do not have organelles or ribosomes
  • The nucleic acid core is encapsulated by a protein coat (capsid) which together forms the head region of the virus.

Life Cycle:

  • A virus attaches to a specific receptor on a cell. Some viruses may now enter the cell, others will inject their nucleic acid
  • The new viral particles may now exit the cell by lysing (bursting).
  • Some viruses lie latent for a long period of time without lysing the host cell and its genome becomes incorporated by genetic recombination into the host’s chromosomes.
  • Therefore, when the host replicates, the viral genome is also replicated.
  • Eventually the virus may become activated and lyse the host cell.
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15
Q

Basic categories of bacteria

(Prokaryotes)

A
  • Prokaryotes
  • no nuclear membrane so transcription and translation can occur at the same time
  • Ribosomes, plasma membrane and a cell wall.
  • Movement with their flagella
  • cocci = spherical and bacilli = rod shaped
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16
Q

What is the equation for bacteria doubling?

A

b = B x 2n

  • b = number of bacteria at the end of time interval
  • B = number of bacteria at the beginning of the time interval
  • n = number of generations
17
Q

What are the similarities and differences between prokaryotic and eukaryotic cells?

A
18
Q

The Genetic Code (triplet)

A

Proteins are long chains formed by peptide bonds between combinations of twenty amino acid subunits. Each amino acid is encoded in a sequence of three nucleotides ( a triplet code = the genetic code)

19
Q

DNA Transcription

A
  1. RNA polymerase moves the transcription bubble, a stretch of unpaired nucleotides, by breaking the bonds between the complementary nucleotides
  2. RNA polymerase adds matching RNA nucleotides that are paired with complementary DNA bases
  3. The extension of the RNA sugar-phosphate backbone is catalyzed by RNA polymerase
  4. Hydrogen bonds of the untwisted RNA + DNA helix break, freeing the newly synthesized RNA strand
  5. If the cell has a nucleus, the RNA is further processed and then exits through the nuclear pore to the cytoplasm
20
Q

RNA Translation

DNA →Transcribed in the nucleus mRNA → Translated in the cytosol Protein

A
  • Translation of mRNA into a protein involves: initiation, elongation and termination
  • Synthesis begins when the ribosome scans the mRNA until it binds to the start codon
  • During elongation, a peptide bond is formed between the existing amino acid in the protein chain and the incoming amino acids. Following peptide bond formation, the ribosome shifts by one codon in the 5’ to 3’ direction along mRNA and the uncharged tRNA in expelled
  • Protein synthesis terminates when the ribosome binds to one of the mRNA termination codons
  • 20 standard amino acids are encoded by the code of 64 codons (43)
  • Degeneracy is the redundancy of the genetic code. Degeneracy occurs because there are more codons than encodable amino acids. The makes the genetic code more tolerant to point mutations.
  • Nonsense mutation = point mutation in a sequence of DNA that results in a premature stop codon. Usually a non-functional protein.
  • Missense mutation = point mutation where a single nucleotide is changed to cause substitution of a different amino acid.
21
Q

Codon/Anticodon Relationship

A

DNA

  • Coding strand = codon
  • Template strand = anticodon

mRNA

  • The message = codons

tRNA

  • The transfer = anticodons

Protein

  • Amino acid

GAMSAT D (6 decks)

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