BIOL500 Test 2

AUT BIOL500 Foundations of Life 2025 Semester 1 Test 2. Doesn't cover everything rip

Mendel’s Laws of Inheritance

Law of segregation, Independent assortment, Law of dominance

Law of Segregation

During gamete formation, the two alleles for each gene segregate randomly so that half of the gametes receive one allele and the rest receive the other.

Independent assortment

During gamete formation, alleles of different genes assort independently of each other, resulting in genetic variation.

Law of Dominance

When contrasting alleles are crossed, only the dominant trait appears in the next generation.

Monogenic trait

A trait influenced by one set of alleles.

Monogenic trait example

Freckles; Widows Peak; Cystic fibrosis

Polygenic trait

Trait influenced by more than one gene

Polygenic trait example

Eye colour; Hair colour; Height

Pedigree

Chart used to trace inheritance patterns in a family

Karyotyping

Examination and analysis of an individual’s chromosomes

Aneuploidy

Abnormal number of chromosomes

Trisomy

Extra chromosome

Monosomy

Lack of chromosome

Polyploidy

Additional set of chromosomes present

Central dogma

Genetic information flows from DNA to RNA to protein

DNA replication

DNA molecule is replicated before cell division

Semi-conservative replication

Each new DNA molecule contains one old and one new strand

Steps of DNA replication

Initiation, elongation, termination

DNA replication initiation

Helicase unwinds double helix at origin of replication, SSBP keep strands separate, Topoisomerase reduces increased coiling, Primase synthesises RNA primer

DNA replication elongation

DNA polymerase adds complementary nucleotides from 5’ to 3’ resulting in leading and lagging strands, removes RNA primers and proofreads, DNA ligase joins okazaki fragments

DNA replication termination

Replication forks meet, new DNA molecules separate

Eukaryotic DNA replication

Occurs in nucleus; Linear DNA has multiple origins of replication; Slower replication rate

Prokaryotic DNA replication

Occurs in nucleoid region; Circular DNA has a single origin of replication; Faster replication rate

Types of RNA

mRNA, tRNA, rRNA

Gene

Section of DNA containing information for molecule synthesis; Unit of heredity

Gene expression in eukaryotes

Transcription occurs inside nucleus; Transcribed mRNA needs to be processed before exiting nucleus; Translation occurs in cytoplasm (rough ER matrix)

Gene expression in prokaryotes

Occurs in cytoplasm; Transcribed mRNA can be translated immediately

Gene structure

Promoter, coding region, terminator

Gene promoter

Region defining where transcription begins

Gene coding region

Encodes RNA and/or protein sequence

Gene terminator

Region defining where transcription stops

Eukaryotic gene structure

Contains introns — non-coding regions spliced out before translation

Prokaryotic gene structure

Lack introns — coding region uninterrupted

Steps of Transcription

Initiation, Elongation, Termination

Transcription initiation

RNA polymerase binds to promoter region, starts at +1 nucleotide, no primer required

Transcription elongation

RNA polymerase adds complementary ribonucleotides to RNA chain (uracil), uses 3’-5’ template while synthesis is 5’-3’

Transcription termination

RNA polymerase, DNA, and mRNA dissociate upon reaching terminator

mRNA in eukaryotes

Transcribed in the nucleus then processed before being transported to cytoplasm for translation

mRNA in prokaryotes

Transcribed directly in the cytoplasm where it is then translated

Coding strand of DNA

Codes for gene of interest

Template strand

Complementary to coding strand, can be transcribed to produce RNA with identical sequence to coding strand

Stages of protein synthesis

initiation, elongation, termination

Translation initiation

Small ribosomal subunit attaches to mRNA, large subunit attaches to small subunit, tRNA start codon enters A-site with complementary anticodon

Translation elongation

tRNA with complementary anticodon moves to P-site, AA from first tRNA joins to second AA, used tRNA moves to E-site to be ejected and recycled. Ribosome moves along mRNA

Translation termination

Stop codon encountered in A-site, release factor enters. H2O molecule added to final position, AA releases. Polypeptide chain undergoes further modification.

Primary structure

Linear sequence of amino acids joined by peptide bonds — protein backbone

Secondary structure

Alpha helices, Beta-sheets

Tertiary structure

3D shape of protein chain, dependent on amino acid composition

Quaternary structure

Multiple polypeptide chains joined to form one functional molecule with multiple subunits

Enzyme

Protein acting as a biological catalyst

RuBisCO

Most abundant enzyme on earth; Crucial role in photosynthesis

DNA polymerase

Enzyme that synthesises new DNA strands using existing DNA as template

RNA polymerase

Synthesises RNA from DNA template

Ribosomes

Synthesise proteins from amino acids

Electron transport proteins

Transfer electrons

ATP synthase

Enzyme converting energy from proton gradients into ATP

Ion channels

Protein structure in cell membrane regulating movement of ions across membrane.

Cellulose synthase

Enzyme synthesising cellulose

Nitrogenase

Catalyses reduction of dinitrogen N2 to ammonia NH3

Metabolism

Sum of all biochemical reactions involved in keeping a cell alive

Metabolic pathways

Series of biochemical reactions that convert molecules, catalysed by enzymes; Product of one reaction becomes the substrate for the next reaction

Metabolites

Molecules involved in metabolic pathway products

Catabolism

Breaking down large nutrient molecules into smaller molecules with simultaneous energy production

Anabolism

Synthesis of larger molecules from smaller ones, energy input generally required

Acetyl coenzyme A

Roles in krebs cycle, fatty acid synthesis, glyoxylate cycle.

Chemiosmosis

Movement of ions (protons) across membrane to generate ATP.

Glyoxylate Cycle

Modified version of krebs cycle in plants and microorganisms

Glyoxylate cycle purpose

Allows plants to convert lipids into glucose, allows microorganisms to convert lipids or simple molucules into polysaccharides for their cell walls

Fatty acid anabolism

Synthesised from Acetyl-CoA via acetate/malonate pathway, allows conversion of carbs into lipids via glycolysis; Glucose to Acetyl-CoA to fatty acids

Fatty acid catabolism

Broken back down to Acetyl-CoA via beta-oxidation pathway, go to krebs cycle for energy production in mitochondrion

Regulation of metabolic pathways

Biochemical regulation, Regulation of rate-limiting step, Cellular regulation, Gene regulation

Biochemical regulation

Product of pathway influences its own production, inhibits enzyme activity to prevent over-accumulation; Feedback inhibition

Regulation of rate-limiting step

Inhibition or enhancement of rate-limiting step has greatest influence on pathway

Cellular regulation

Done via cell-signalling pathways like hormones

Gene regulation

Turn genes on or off depending on environmental or cellular signals

Photosynthesis

Plants convert carbon dioxide and water into glucose and oxygen using the energy of sunlight

Respiration

Plants and animals use plant-derived glucose to ‘reverse’ photosynthesis to release energy

Light-dependent reactions

Light energy is absorbed by chlorophyll, used to make ATP and NADPH

Light-independent reactions

ATP and NADPH are used to convert carbon dioxide into glucose

Site of light-dependent reactions

Thylakoid membrane of the chloroplast

Site of Calvin cycle

Stroma of the chloroplast

Chemiosmosis in eukaryotes

Occurs in inner mitochondrial membrane and thylakoid membrane of chloroplast

Chemiosmosis in prokaryotes

Occurs across plasma membrane