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Anatomy and Physiology > Cell Biology Lecture 3 > Flashcards

Cell Biology Lecture 3 Flashcards

1
Q

Overview of Protein Synthesis

A
  • Making new proteins from the genome.
  • Occurs only in cells with a nucleus.
  • Protein synthesis begins in the nucleus and ends in the cytoplasm.
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2
Q

Steps of Protein Synthesis

A
  • Transcription (DNA → mRNA).
  • Translation (mRNA → protein).
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3
Q

Transcription Overview

A
  • Transcribing DNA into RNA.
  • Three types of RNA can be formed.
  • Takes place in the nucleus.
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4
Q

Transcription Steps

1-8

A

Step 1: RNA polymerase begins at the promoter region.
Step 2: Complementary bases match on the template strand.
Step 3: Process continues until the terminator region.
Step 4: RNA polymerase detaches from pre-mRNA and DNA.
Step 5: Editing with snRNPs (splicing) and addition of 5’ cap and 3’ poly-A tail.
Step 6: Attachment of a 5’ cap.
Step 7: Attachment of a 3’ poly-A tail.
Step 8: Mature mRNA exits the nucleus for translation.

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5
Q

Translation Overview

A
  • Translating mRNA to a polypeptide (protein).
  • Carried out by ribosomes.
  • Occurs in the cytoplasm.
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6
Q

Translation Steps

A

Step 1: mRNA attaches to the small ribosomal subunit.
Step 2: Large ribosomal subunit attaches to create a functional ribosome.
Step 3-5: Anticodon of tRNA pairs with mRNA codon, peptide bond forms, di-peptide protein forms.
Step 6-7: Ribosome shifts mRNA, translation ends at a stop codon.

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7
Q

Translation Recap

A
  • mRNA → protein in the cytosol.
  • Involves mRNA, rRNA, and tRNA.
  • Amino acid order determined by mRNA codons.
  • Some ribosomes free in the cytosol, some attached to the ER (rough ER).
  • Polyribosomes (polysomes) may translate the same mRNA simultaneously for efficiency.
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8
Q

Cell Division Overview

A
  • Process of replication and division for the formation of new daughter cells.
  • Two major types: Mitosis and Meiosis.
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9
Q

Purpose of Mitosis and Meiosis

A
  • Mitosis: Creates identical cell replicas for growth and repair.
  • Meiosis: Creates gametes (sperm and ova) for sexual reproduction.
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10
Q

Diploid vs. Haploid

A
  • Nearly all human cells have 46 chromosomes (2n).
  • Gametes have 23 chromosomes (n).
  • Mitosis involves diploid cells becoming diploid cells.
  • Meiosis involves diploid germ cells becoming haploid gamete cells.
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11
Q

The Cell Cycle

A
  • Series of events in cell replication and division.
  • Involves Interphase and Mitotic/Meiotic Phase.
  • Meiosis goes through two rounds of cell division.
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12
Q

Mitosis Overview

A
  • Replicates and divides somatic cells.
  • Involves Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
  • Starts and ends with diploid cells.
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13
Q

Mitosis Phases - Interphase

G1 Phases, S Phase, G2 Phase

A
  • G1 Phase: Growth, organelle duplication, centrosome replication.
  • S Phase: DNA replication.
  • G2 Phase: Continued growth, protein synthesis.
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14
Q

Mitosis Phases - Prophase

A
  • Chromatin condenses into chromosomes.
  • Sister chromatids unite.
  • Nuclear envelope breaks down, centrosomes migrate.
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15
Q

Mitosis Phases - Metaphase

A

Chromosomes line up along the metaphasic plate.

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16
Q

Mitosis Phases - Anaphase

A
  • Centromeres split, sister chromatids separate.
  • Cleavage furrow forms.
17
Q

Mitosis Phases - Telophase and Cytokinesis

A
  • Cleavage furrow grows, chromatids at poles.
  • Nuclear envelope reforms, cytokinesis completes
18
Q

Mitosis Recap

A
  • Starts with diploid cell.
  • Organelle duplication and DNA replication during interphase.
  • Ends with two identical diploid daughter cells.
19
Q

Meiosis Overview

A
  • Produces four non-identical, but similar gametes.
  • Involves Meiosis I and Meiosis II.
  • Takes place in gonads (testicles, ovaries).
20
Q

Meiosis Phases - Prophase I

A

Chromosomes form tetrads, undergo crossing over.

21
Q

Meiosis Phases - Metaphase I

A

Tetrads line up on the metaphasic plate.

22
Q

Meiosis Phases - Anaphase I

A

Homologous chromosomes separate, sister chromatids remain together.

23
Q

Meiosis Phases - Telophase I and Cytokinesis

A

Results in two gametes with haploid chromosomes.

24
Q

Meiosis II Phases

A
  • Prophase II: No tetrads or synapse formation.
  • Metaphase II: Chromosomes line up.
  • Anaphase II: Sister chromatids split.
  • Telophase II: Similar to mitosis telophase.
25
Q

Meiosis Recap

A
  • Starts with diploid germ cells.
  • Ends with four non-identical, similar haploid gametes.
26
Q

Mitosis vs. Meiosis

A
  • Mitosis: Produces two identical diploid cells.
  • Meiosis: Produces four non-identical haploid gametes.
27
Q

Germ Cells

A
  • Born with diploid germ cells.
  • Called spermatogonia and oogonia.
  • Have 46 chromosomes (2n).
28
Q

Mitosis and Primary Cells

A
  • Germ cells undergo mitosis, forming primary spermatocytes and primary oocytes (diploid, 2n).
  • Primary cells enter meiosis to become gametes (sperm and ova).
29
Q

Spermatogenesis in Males

A
  • Puberty triggers primary spermatocytes to enter meiosis I and II immediately.
  • Results in the production of spermatids, each with 23 chromosomes.
  • Spermatids undergo spermiogenesis to become mature sperm (spermatozoa).
30
Q

Spermiogenesis

A
  • Spermatids undergo changes to form mature sperm.
  • Changes include developing distinct regions (head, midpiece, tail), forming a fully functional tail (flagella), and creating an acrosomal cap.
31
Q

Oogenesis in Females

A
  • Oogonium mitosis is complete before birth.
  • Limited supply of primary oocytes (about 2 million at birth, 400,000 by puberty).
  • Primary oocyte begins meiosis I in fetal development, arrested until puberty.
  • Each month, 6-20 primary oocytes complete meiosis I and enter meiosis II, finishing only if fertilized.
32
Q

Reproductive Vocabulary

A

Gamete: Sperm or ovum with 23 chromosomes.
Zygote: Union of 2 gametes (now 46 chromosomes).
Blastocyst: Zygote divides into an 8-celled blastocyst, implanting into the uterine wall.

Anatomy and Physiology (21 decks)

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