EXAM

• Animal cell structures

  A) Nucleus

  B) Centrioles

  C) Lysosomes

  D) Mitochondrion

  E) Cell membrane

  F) Cytosol

  G) Endoplasmic reticulum

  H) Ribosomes

  I) Golgi body

  
• Plant cell structures

  A) Cytosol

  B) Ribosomes

  C) Mitochondrion

  D) Cell wall

  E) Cell membrane

  F) Chloroplast

  G) Nucleus

  H) Endoplasmic Reticulum

  I) Golgi body

  
• Characteristics of living organisms: 

  M - moves: on it’s own accord

  S - sensitive: detects, reacts, and responds to changes in it’s environment

  G - grows: makes new cells (mitosis)

  R - reproduces: makes new offspring (sexually/asexually)

  E - exchanges gasses: O2, Co2, respiration, photosynthesis 

  E - excretes waste: removal of toxic materials

  N - nutritional input: chemical input for energy and reactions 

  • Organic: carbohydrates, proteins, fats
  • Inorganic: minerals, water, vitamins 
• Cell theory: 

  • All organisms are made of cells (building blocks)
  • Cells are the smallest functioning unit of living organisms (that works independently)
  • All cells come from pre-existing cells (mitosis) 
• Types of cells: 

  • Prokaryotic: Do not contain a nucleus (no internal membrane structures)

  Eg., monera (bacteria)

  • Eukaryotic: contains a nucleus surrounded by a membrane (has internal membrane structures)

  Eg., animals, plants, fungi, protista  

  
  

  Types of cells: 

  • Unicellular: consists of one cell only 
  • Multicellular: consists of many cells

  Cells of one type performing the same function are called tissue

  Cells -> Tissue -> Organ -> System
• Plant:

  • Cell wall
  • Chloroplast

  Animal:

  • Lysosome
  • Centriole

  Both: 

  • Cell membrane
  • Nucleus
  • Mitochondrion
  • Ribosome
  • Cytosol
  • Endoplasmic reticulum 
  • Golgi body
  • Vacuole: P - big, A - small
• Cell wall: Support and protection 
• Cell membrane: Flexible barrier that regulates movement of molecules in and out of the cell
• Nucleus: Holds DNA which controls cell activities 
• Mitochondrion: Where energy (ATP) is produced from glucose in cellular respiration
• Chloroplast: Site of photosynthesis to convert light energy into glucose 
• Ribosome: Site of protein synthesis 
• Cytosol: Jelly fluid where many cell reactions happen
• Endoplasmic reticulum: Transports material within the cell
• Golgi body: Packages materials for storage and secretion 
• Vacuole: Storage area for water, starch, oils, etc., - large in plant cells 
• Lysosome: Packets of enzymes that are released to kill old / malfunctioning cells (apoptosis)
• Centriole: Structure involved in cell division
• Cell order:

  Cells -> Nucleus -> Chromosome -> DNA -> Gene
• Nucleotide structure:

  A) Phosphate

  B) Deoxyribose sugar

  C) Nitrogen base

  
• DNA (deoxyribonucleic acid): 

  • A double helix made of nucleotides, found in the nucleus of eukaryotic cells; the molecule that determines the genetic characteristics of most living things
• The ‘rungs’ of the DNA ladder are made out of the four nitrogen-rich bases:

  • Adenine 
  • Thymine 
  • Guanine 
  • Cytosine 
• Phosphodiester bonds:

  • Strong bonds between the sugar of one nucleotide and the phosphate of the next nucleotide  
  • Form the sugar / phosphate sides
• Complementary base pairing rule: 

  The bases are joined together by weak hydrogen bonds

  • A pairs with T (2 bonds)
  • G pairs with C (3 bonds) 
• Chromosome: 

  • Incredibly long threads of DNA are tightly coiled around each other and proteins (histones)
• Labelled chromosome:

  A) Centromere

  B) Chromatids

  
• Gene: 

  • A section of DNA arranged along the chromosome that carries the genetic code for a specific protein or trait

  These proteins create structures and perform actions needed for cells to survive, grow, and function. 

  For example these proteins may be:

  • Structural, eg., collagen 
  • Enzymes, eg., pepsin
  • Regulatory, eg., insulin
• Chromosomes in humans: 

  • 46 chromosomes in every cell

  -> 44 regular, 2 sex  

  
  

  
  

  Gametes (egg cells in females, sperm cells in males) have half the number of chromosomes:

  • 22 chromosomes, 1 sex chromosome 
• Homologous chromosomes: Chromosome pairs that have the same gene order

  • Same position of genes
  • Same length
  • Same position of the centromere
• Types of chromosomes

  Autosomes: 

  • Chromosomes that carry genes for general characteristics
  • No differences in gender
  • Humans have 44 (22 pairs)

  Sex chromosomes:

  • Genes for sex are located here
  • Humans have 2: XX for female, XY for male
• Karyotype: A picture of someone’s chromosomes

  1. Chromosomes are dyed
  2. Chromosomes are arranged in order in homologous pairs 

  Karyotyping is used to determine: 

  • Gender
  • Chromosomal abnormalities
• Cell division involves forming new cells

  There are 2 main type of division:

  • Mitosis: one diploid cell dividing into two identical diploid cells (for the purpose of growth, repair and replacement)
  • Meiosis: one diploid cell dividing into four haploid cells (non-identical, for the purpose of making gametes)

  For both types of division, every chromosome (DNA molecule) needs to be copied to then put one copy in each new cell
• DNA replication: 

  1. DNA unzips and unwinds with the help of enzymes
  2. Free nucleotides in the nucleus join to bases on the DNA molecule that now have no partner using the complementary base pairing rule
  3. This continues down the molecule until the whole thing has been replicated
  4. There are now two identical DNA molecules

  *Mistakes can happen = mutations
• Mitosis: 

  • Formation of new somatic cells 
  • Used for growth, repair, and replacement 
  • Used for asexual reproduction. 
  • From each diploid cell, 2 genetically identical diploid cells are produced

  Stages of mitosis: 

  PARENT CELL

  • DNA replication (not mitosis)

  1. Chromosomes align in the middle of the cell
  2. Chromatids separate, go to each end of the cell
  3. Physical division of cell into two identical daughter cells 

  DAUGHTER CELLS
• Meiosis: 

  • Formation of new gametes (egg and sperm)
  • Used for sexual reproduction
  • From each diploid ovary or tests (gonad) germline cell, 4 haploid cells are produced

  Stages of meiosis: 

  • DNA replication (not meiosis)

  1. Chromosomes line up side by side in cell
  2. First division splits number of chromosomes
  3. Chromosomes align in the middle of the cell
  4. Chromatids separate and go to each end of the cell
  5. Physical division two into four unique daughter cells
• We inherit:

  • Two genes for each trait
  • One from maternal origin, one from paternal origin
• Gene:

  • A section of DNA that carries the genetic code for a particular characteristic 
• Allele:

  • Different forms of the same gene / variation of a gene, due to different sequence of base pairs
• Genotype:

  • The combination of alleles that an individual has which is denoted by letters (e.g. AA, Aa, aa)
• Homozygous / pure breeding:

  • The individual has inherited two alleles for a trait that are the SAME (e.g. AA or aa)

  Heterozygous / hybrid:

  • The individual has inherited two alleles for a trait that are DIFFERENT (e.g. Aa)