B13-Reproduction Flashcards
(38 cards)
What is asexual reproduction?
Asexual reproduction involves one parent and produces offspring that are genetically identical to the parent. This happens through processes like mitosis.The products are clones.
What is sexual reproduction?
Sexual reproduction involves two parents and the fusion of gametes
(sex cells)to produce offspring that are genetically different from either parent. It involves process like meiosis.
Explain Meiosis
Interphase: The cell prepares for division, duplicating its chromosomes.
Meiosis I: Chromosomes pair up and exchange genetic material
crossing over, increasing genetic diversity. The pairs separate, resulting in two daughter cells, each with half the original number of chromosomes.
Meiosis II: Similar to mitosis, the chromosomes in each daughter cell separate. This results in four daughter cells, each with a single set of chromosomes haploid.
What is the different between haploid and diploid cells?
Haploids have one set of chromosomes, while diploids have two sets.
Explain fertilisation and its importance in reproduction?
Fertilisation is the process where the male gamete
(sperm) fuses with the female gamete (egg) to form a zygote. This initiates the development of a new organism as meiosis occurs after.
How does sexual reproduction increase genetic variation?
Crossing Over: During meiosis, chromosomes exchange genetic material. This means that the chromosomes you inherit aren’t just from one parent or the other, but a mix of both.
Independent Assortment: During meiosis, homologous chromosomes line up randomly. This random alignment means that the daughter cells get a mix of maternal and paternal chromosomes.
Mutation: Although not exclusive to meiosis, mutations can occur during DNA replication before meiosis, introducing new alleles.
What is the difference between genes and alleles?
Genes: A gene is a specific sequence of DNA that codes for a particular trait or characteristic. Think of it as a blueprint or instruction manual for building a specific protein or performing a specific function in the body. Genes are located on chromosomes.
Alleles: Alleles are different versions of the same gene. For example, a gene might determine eye colour, but different alleles of that gene could specify blue eyes, brown eyes, or green eyes. You inherit one allele from each parent for each gene.
What are chromosomes?
Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. They are made of protein and a single molecule of DNA. DNA contains the specific instructions that make each type of living creature unique. Each chromosome is made of DNA tightly coiled many times around proteins called histones that support its structure
Advantages and disadvantages of asexual reproduction:
Advantages:
Speed: Asexual reproduction is generally faster than sexual reproduction.
Simplicity: It requires only one parent.
Efficiency: In a stable environment, asexual reproduction allows for the rapid production of many offspring that are well-suited to that environment.
No need for a mate: Organisms don’t need to expend energy finding a partner.
Disadvantages:
Lack of genetic diversity: Offspring are genetically identical to the parent clones, so there’s little variation. This makes the population vulnerable to changes in the environment or new diseases.
Advantages and Disadvantages of sexual reproduction?
Advantages:
Genetic diversity: Offspring inherit a mix of genes from both parents, leading to genetic variation. This variation increases the chances that some individuals will be well-suited to a changing environment.
Adaptation: Genetic diversity allows populations to adapt to new conditions and resist diseases more effectively.
Disadvantages:
Slower process: Sexual reproduction is generally slower and more complex than asexual reproduction.
Need for a mate: Organisms must expend energy finding and attracting a mate.
Less efficient: Only half of the parent’s genes are passed on to each offspring.
Energy expenditure: Processes like meiosis and fertilisation require significant energy.
What is the genome?
A genome is the complete set of genetic instructions in a cell, including all of its genes and DNA.
What were the aims of the human genome project?
Identifying all the approximately 20,000-25,000 genes in human DNA.
Determining the sequences of the 3 billion chemical base pairs that make up human DNA.
Storing this information in databases.
Improving tools for data analysis.
Why is studying the genome important?
Understanding diseases: Identifying genes linked to diseases can help in diagnosis, treatment, and prevention.
Drug development: Understanding how genes interact with drugs can lead to more effective and personalised medicine.
Evolutionary relationships: Comparing genomes reveals how species are related and how they have evolved over time.
Personalised medicine: Tailoring medical treatment to an individual’s genetic makeup
What is DNA and describe its structure?
DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms.
Structure:
DNA has a double helix structure, which looks like a twisted ladder.
Backbone: The sides of the ladder are made of a sugar-phosphate backbone.
Rungs: The rungs of the ladder are made of pairs of nitrogenous bases. There are four types of nitrogenous bases: Adenine A, Thymine T, Guanine G, Cytosine C
A always pairs with T, and G always pairs with C. These are called complementary base pairs.
What is DNA’s role?
The main role of DNA is to store and transmit genetic information. This information is used to create proteins, which carry out various functions in the body. DNA also plays a role in:
Heredity: Passing genetic information from parents to offspring.
Cell growth and division: DNA is replicated during cell division to ensure that each new cell has a complete copy of the genetic information.
Protein synthesis: DNA contains the instructions for making proteins.
Genetic variation: Differences in DNA sequences lead to genetic variation among individuals.
Explain protein synthesis?
DNA as the Blueprint: DNA contains genes, which are specific sequences of nucleotides that code for particular proteins. Think of DNA as the master blueprint for building all the proteins a cell needs.
Transcription: The first step is transcription, where the DNA sequence of a gene is copied into a messenger RNA (mRNA) molecule. This process occurs in the nucleus. The mRNA acts as a mobile copy of the gene’s instructions.
mRNA Transport: The mRNA molecule then leaves the nucleus and travels to the ribosomes in the cytoplasm. Ribosomes are the sites of protein synthesis.
Translation: At the ribosome, the mRNA sequence is translated into an amino acid sequence. Transfer RNA (tRNA) molecules bring specific amino acids to the ribosome, matching them to the mRNA codons (three−nucleotidesequences). Each codon specifies a particular amino acid.
Protein Assembly: As the ribosome moves along the mRNA, the amino acids are linked together by peptide bonds, forming a polypeptide chain. This chain folds into a specific three-dimensional structure, becoming a functional protein.
What is gene expression?
The process by which information from a gene is used to synthesize a functional product (protein or RNA).
Key Stages:
Transcription (DNA → RNA)
Translation (RNA → Protein)
What are codons and their function?
A sequence of three consecutive nucleotides in a DNA or RNA molecule that codes for a specific amino acid. Certain codons signal the start or end of translation. These are called start or stop (or termination) codons.
What happens to the proteins after being synthesised?
Enzymes: Catalysing biochemical reactions.
Structural components: Providing support and shape to cells and tissues.
Hormones: Signalling molecules that regulate physiological processes.
Antibodies: Defending the body against foreign invaders.
Transport molecules: Carrying molecules across cell membranes or within the body.
Difference between genotype and phenotype?
Genotype refers to the genetic makeup of an organism, while phenotype refers to the observable characteristics of an organism. Genotype determines the potential range of phenotypes, but the actual phenotype is also influenced by environmental factors.
What are mutations?
Mutations are changes in the DNA sequence of an organism. These changes can be caused by errors during DNA replication, exposure to mutagens like radiation or certain chemicals, or even spontaneous events. Mutations can be harmful, beneficial, or have no noticeable effect.
What do non coding DNA do ?
Non-coding parts of genes, also known as non-coding DNA, have a variety of functions. These regions don’t code for proteins, but they play crucial roles in regulating gene expression and maintaining genome structure.
Regulation of Gene Expression: Many non-coding regions contain regulatory elements like promoters, enhancers, and silencers. These elements control when, where, and how much a gene is transcribed.
Structural Roles: Some non-coding regions are involved in maintaining the structure of chromosomes. For example, telomeres protect the ends of chromosomes, and centromeres are essential for chromosome segregation during cell division.
Allows one gene to produce multiple proteins via alternative splicing.
What is epigenetics?
The study of heritable changes in gene expression without altering the DNA sequence. These changes are caused by chemical modifications (e.g., DNA methylation, histone acetylation) that turn genes “on” or “off.”
How does epigenetics affect gene expression?
Chemical modifications (e.g., DNA methylation, histone acetylation) that alter gene activity without changing DNA sequence.
Methylation: Silences genes.
Acetylation: Activates genes.
