DNA Biochemistry Quiz

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Questions and Answers

What is the primary function of nucleic acids?

To store and transmit genetic information (correct)

To facilitate cell division

To provide structural support to cells

To regulate enzyme activity

During which phase of meiosis does crossing over occur?

Prophase I (correct)

Metaphase I

Anaphase I

Telophase I

How does a frameshift mutation occur?

By substituting one base for another

By a duplication of a DNA segment

By rearranging chromosome structures

By adding or deleting a nucleotide (correct)

What is the outcome of meiosis in terms of the chromosome count of the resulting cells?

Haploid cells with half the chromosome number Signup and view all the answers

What is the primary difference between homologous chromosomes and sister chromatids?

Sister chromatids are formed during DNA replication, while homologous chromosomes are inherited from each parent Signup and view all the answers

In which location does transcription occur in eukaryotic cells?

Nucleus Signup and view all the answers

What type of gametes do male gonads produce?

Sperms Signup and view all the answers

What is a polar body in female meiosis?

A non-functional cell that receives minimal cytoplasm Signup and view all the answers

What process does the zygote undergo immediately after fertilization?

Cleavage Signup and view all the answers

During which trimester does organogenesis primarily occur?

First trimester Signup and view all the answers

What is the main purpose of Mendel’s First Law of Segregation?

To describe how alleles are distributed during gamete formation Signup and view all the answers

Which of the following best describes co-dominance?

Both alleles are expressed equally in the phenotype Signup and view all the answers

Which stage follows the formation of the blastula during embryonic development?

Gastrulation Signup and view all the answers

What differentiates a homozygous genotype from a heterozygous genotype?

Homozygous alleles are identical, while heterozygous alleles are different Signup and view all the answers

What is the likely outcome when two parents with a genotype of Aa and Aa are crossed?

25% will be homozygous recessive and 50% will be heterozygous Signup and view all the answers

Which component of seminal fluid is primarily produced in the seminal vesicles?

Fructose Signup and view all the answers

Study Notes

DNA Biochemistry

Gene: A segment of DNA that codes for a specific protein or functional RNA molecule.
Allele: Alternative forms of a gene that occupy the same locus (position) on a chromosome.
Nucleic Acid: A type of biomolecule composed of nucleotides.
- 3 Parts of a Nucleotide:
  - Phosphate group
  - Pentose sugar (either ribose or deoxyribose)
  - Nitrogenous base (adenine, guanine, cytosine, thymine, or uracil)
- Function: Store and transmit genetic information.
DNA Molecule:
- Function: Carries the genetic instructions used in the development and functioning of all known living organisms.
- Parts:
  - Deoxyribose sugar
  - Phosphate group
  - Nitrogenous bases: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
- Structure: Double helix, two strands running antiparallel, held together by hydrogen bonds between complementary base pairs.
  - Base Pairing: Adenine pairs with Thymine (A-T), Guanine pairs with Cytosine (G-C).
- DNA Replication:
  - Process: The DNA molecule unwinds and each strand serves as a template for the synthesis of a new complementary strand.
    - DNA polymerase is the enzyme that adds nucleotides to the new strand.
  - DNA Repair: Enzymes identify, remove, and replace incorrectly paired or damaged nucleotides.
RNA Molecule:
- Function: Carry genetic information from DNA to ribosomes for protein synthesis.
- Types: Messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA).
- Differences from DNA:
  - Sugar: Contains ribose sugar instead of deoxyribose.
  - Base: Contains uracil (U) instead of thymine (T).
  - Structure: Single-stranded, usually folded into a complex shape.

Central Dogma of Molecular Biology

Describes the flow of genetic information from DNA to RNA to protein.
Transcription: The process of copying DNA into RNA. Takes place in the nucleus.
- Molecules involved: RNA polymerase, DNA, mRNA.
Translation: The process of converting mRNA into a protein. Takes place in the cytoplasm at ribosomes.
- Molecules involved: mRNA, tRNA, ribosomes, amino acids.
Mutations: Permanent changes in the DNA sequence.
- Definition: Changes in the genetic code.
- Types:
  - Point mutations: Changes in a single nucleotide.
    - Frameshift mutations: Insertions or deletions that shift the reading frame of the genetic code.
      - Insertions: Adding an extra nucleotide.
      - Deletions: Removing a nucleotide.
    - Substitution mutations: Replace one nucleotide with another.
      - Silent mutations: Do not change the amino acid sequence of the protein.

Meiosis

Location:
- Males: Testes (gonads)
- Females: Ovaries (gonads)
Sex Cells:
- Males: Sperm
- Females: Egg (ovum)
Purpose: To produce gametes (sperm and egg) with half the number of chromosomes as the parent cell.
Haploid vs. Diploid:
- Haploid: Cells with one set of chromosomes (n).
- Diploid: Cells with two sets of chromosomes (2n).
Sister Chromatid: Identical copies of a chromosome that are attached at the centromere before cell division.
Homologous Pairs: Two chromosomes that have the same genes but different alleles.
Crossing Over: The exchange of genetic material between homologous chromosomes during prophase I of meiosis.
First Interphase: The cell grows and replicates its DNA.
Meiosis I:
- Prophase I: Chromosomes condense, homologous chromosomes pair up and exchange genetic material (crossing over), the nuclear envelope breaks down.
- Metaphase I: Homologous pairs line up at the metaphase plate, spindle fibers attach to the centromeres.
- Anaphase I: Homologous chromosomes separate and move to opposite poles of the cell.
- Telophase I: Chromosomes reach the poles, the cytoplasm divides, and two daughter cells are formed.
Interphase II: A brief interphase, no DNA replication occurs.
Meiosis II:
- Prophase II: Chromosomes condense, the nuclear envelope breaks down.
- Metaphase II: Sister chromatids line up at the metaphase plate, spindle fibers attach to the centromeres.
- Anaphase II: Sister chromatids separate and move to opposite poles of the cell.
- Telophase II: Chromosomes reach the poles, the cytoplasm divides, and four haploid daughter cells are formed.
Meiosis in Female Animals:
- Polar Bodies: Small, non-functional cells produced during oogenesis (egg formation).
- Asymmetrical cell division ensures that the egg receives most of the cytoplasm and organelles for proper development.

Sex and Development

Gonads: The organs that produce gametes.
Gametes: Sex cells (sperm and egg).
Male Reproductive Anatomy:
- Sperm Production Pathway:
  - Testes: Produce sperm.
  - Epididymis: Where sperm mature and are stored.
  - Vas deferens: Carries sperm from the epididymis to the urethra.
  - Seminal vesicles: Secrete a sugary fluid that provides energy for sperm.
  - Prostate gland: Secretes a milky fluid that neutralizes the acidity of the vagina.
  - Bulbourethral gland: Secretes a clear mucus that lubricates the urethra.
- Sperm Components:
  - Head: Contains the nucleus with DNA.
  - Midpiece: Contains mitochondria for energy production.
  - Tail: Allows for movement.
Female Reproductive Anatomy:
- Egg Production Pathway:
  - Ovaries: Produce eggs.
  - Fallopian tubes: Site of fertilization.
  - Uterus: Where the fertilized egg implants and develops.
  - Cervix: The opening of the uterus.
  - Vagina: The birth canal and the site of sperm deposition.
Fertilization: The fusion of sperm and egg to form a zygote.

Developmental Stages

Zygote: The fertilized egg.
Cleavage: Series of rapid cell divisions that increase the number of cells but not the overall size of the embryo.
- Formation of blastula/blastocyst: Hollow ball of cells.
  - Blastocyst: A stage of development where the embryo differentiates into the inner cell mass (ICM) and the outer trophoblast.
Gastrulation: Formation of the three germ layers:
- Ectoderm: Forms the skin, nervous system.
- Mesoderm: Forms muscles, bones, blood vessels.
- Endoderm: Forms digestive system, lungs.
Neurulation: Formation of the neural tube, which will develop into the central nervous system.
Notochord: A rod-shaped structure that supports the embryo and will later develop into the vertebral column.
Trimesters of Pregnancy:
- First Trimester (0-12 weeks): Organogenesis, significant growth, a period of high risk
- Second Trimester (13-27 weeks): Continued growth, some development.
- Third Trimester (28-40 weeks): Significant growth and development of the nervous system and lungs.
Childbirth:
- Stage 1: Dilation of the cervix (6-24 hours).
- Stage 2: Delivery of the baby (20 minutes to 2 hours).
- Stage 3: Delivery of the placenta (5 to 30 minutes).

Mendelian Genetics

Gene: A segment of DNA that codes for a specific protein or functional RNA molecule.
Allele: Alternative forms of a gene that occupy the same locus (position) on a chromosome.
Genotype: The genetic makeup of an individual.
Phenotype: The observable characteristics of an individual.
Homozygous: Having two identical alleles for a trait.
Heterozygous: Having two different alleles for a trait.
Dominant: An allele that masks the expression of the recessive allele.
Recessive: An allele that is only expressed when two copies are present.
Mendel's First Law (Law of Segregation): During gamete formation, the two alleles for a gene segregate so that each gamete receives only one allele.
Mendel's Second Law (Law of Independent Assortment): Alleles for different genes assort independently of one another during gamete formation.
Punnett Squares: A diagram used to predict the possible genotypes and phenotypes of offspring.
Incomplete Dominance: A heterozygous genotype results in a phenotype that is a blend of the two homozygous phenotypes.
Co-dominance: Both alleles for a trait are expressed in the heterozygous phenotype.
Pleiotropy: One gene influences multiple traits.
Polygenic Traits: Traits influenced by multiple genes.
Environmental Influence: The environment can influence the expression of genes.
Chromosomal Theory of Inheritance: Genes are located on chromosomes.
Chromosome vs. DNA vs. Gene:
- Chromosomes: Made up of DNA and proteins.
- DNA: The molecule that carries genetic information.
- Genes: Segments of DNA that code for specific traits.
Autosomes: The chromosomes that are not sex chromosomes.
Sex Chromosomes: The chromosomes that determine sex (X and Y in humans).

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Description

Test your knowledge on the fundamental concepts of DNA biochemistry, including genes, alleles, nucleic acids, and the structure and function of DNA. This quiz covers key terms and their roles in genetics. Perfect for students learning about molecular biology.