HS133 Cell Structure, Genetics, and Basic Embryology PDF

HS133: Introduction to cell structures and basic genetics Session outline Basic cell structure Basic genetics Basic embryology Workshop activity Levels of structural organization (Marieb and Keller, 2018, p.29, fig 1.1) Cells - introduction Basic unit of life All have common structure...

HS133: Introduction to cell structures and basic genetics Session outline Basic cell structure Basic genetics Basic embryology Workshop activity Levels of structural organization (Marieb and Keller, 2018, p.29, fig 1.1) Cells - introduction Basic unit of life All have common structures Vary in size, shape, functions in the body Plant vs. animal cells Organisms can be: Unicellular Multicellular organisms Some cells of the human body (Peate and Nair, 2017, p.30, fig 2.1 ) Animal cell compartments (Peate and Nair, 2017, p31, fig 2.1) Plasma/Cell membrane Phospholipid bilayer Establishes the cell boundary and separates cell from environment Function: transport and communication Transports into the cell: oxygen, electrolytes, water, hormones Transports out of the cell: waste products (e.g. carbon dioxide, urea) Forms of cell signalling (Access Excellence, nd)  Nucleus Cell’s “command centre” Sends instructions for cell growth, division, death Houses DNA (deoxyribonucleic acid) – cell’s hereditary material Complex molecule Made up of multiple simpler molecules Nitrogen base Carbon-based sugar molecule (deoxyribose) Phosphate group (Marieb and Keller, 2018, p.90, fig 3.1) DNA structure (Nature Education, 2014, fig 1,2,3,4,6) Key terms: Chromatin and Chromosomes Chromatin – housed in the nucleus Complex made up of DNA double helix packed around proteins Found in all stages of cell cycle Condenses during cell division to become chromosomes Chromosome – single-stranded groupings of condensed chromatin Replicates so that each daughter cell receives correct number of chromosomes (Diagnostics, 2017; Diffen, nd) Duplicated chromosome Chromosome structure 1) Chromatid 2) Centromere 3) Short arm 4) Long arm Chromatid – each “strand” of a replicated chromosome “Sister chromatids” – chromatids (Tryphon, 2008) connected by the centromere (Diagnostics, 2017; Diffen, nd) (Peate and Nair, 2017, p65, fig 3.3)  A typical body cell contains 23 pairs of chromosomes – 46 in total 22 pairs are homologous (look-alike) and Chromosomes autosomes - carry genes/codes to determine body traits 1 pair is the sex chromosome – carries genes/codes to determine sex (male or female) Females – XX Males – XY  Daughter cell after fertilization (Khan Academy, nd) Cell division – Quick note After cell division, sex cells have half of the genetic material – 23 individual chromosomes When egg and sperm combine, individual chromosomes pair up again resulting in 23 chromosome pairs Mitosis vs Meiosis comparison Mitosis & Meiosis Summary Chart Mitosis vs Meiosis (Khan Academy) (Rouse, 2020, p. 47, fig 3-2)  Each pair of chromosomes represents the genotype (genetic information) that informs the phenotype (what they look like) Codes for (BYJU, nd) Gene Basic unit of heredity Carry information that determines traits A certain section of DNA Every person has 2 copies of each gene 1 inherited from each parent DNA in a gene provides instructions for making proteins Different forms of the same gene are called alleles E.g. brown, blue, green eye colour (National Institutes of Health, 2019)  Gene expression Dominant allele – phenotypically expressed over another allele Recessive allele – only expressed in absence of dominant allele (FamilyEducation, nd) Gene expression Codominant allele – allow expression of both alleles Sex linked genes – genes carried by either sex chromosome (e.g. haemophilia) (O’Neil, 2012)  Disease caused by a change in the DNA sequence Inherited or non-inherited Mutations can occur randomly or due to environmental factors Genetic Single gene disorders – e.g. Huntington’s disease, Cystic disorders Fibrosis Chromosome disorders – e.g. Down’s syndrome, Turner syndrome Multifactorial disorders – e.g. Alzheimer’s disease, cancer  Name some genetic syndromes you might come across as an SLT Basic embryology Fertilization Spermatozoon (male gamete) and an ovum (female gamete) join to form a single cell (zygote) Takes place in the Fallopian tube Stages of development: Preembryonic period Embryonic period Foetal period Preembryonic period Zygote undergoes cleavage (series of rapid mitotic divisions) Eventually zygote develops into a blastocyst Trophoblast layer Develops into foetal membranes and placenta Blastocyst cavity Inner cell mass Later forms the embryo (late blastocyst) Blastocyst attaches to the endometrium (Clancy and McVicar, 2009, p. 524, fig 19.3) Embryonic development Three germ layers are being formed: Ectoderm Epidermis, nervous system, pituitary and salivary glands, optic lens, hair, enamel Mesoderm Connective and supportive tissue, blood and vascular system, musculature, teeth (except enamel), kidneys, ureters (Marieb and Keller, 2018, p. 587, fig 16.18) Endoderm Pharynx, trachea, auditory canal, alimentary canal, liver, pancreas, bladder, urethra, prostate Foetal development  Clinical note Potentially sensitive topic warning Cleft Lip and/or Palate Cleft – gap/split, present from birth Present from birth As the baby develops, body tissue and special cells from each side of the head grow towards the centre of the face and join together Cleft arises because a baby’s face did not join together properly during development in the womb Lips forms between 5 – 7th week of pregnancy Palate (roof of the mouth) forms between 6th – 9th week of pregnancy (Institute of Medical Illustrators, 2018, fig 2) Cleft Lip and/or Palate Prevalence: 1 in 700 (UK) Proportion of a population who has a specific characteristic in a given time Causes - genetic and environmental factors Sometimes associated with other conditions Diagnosis Cleft lip: mid-pregnancy anomaly scan Cleft palate: usually undiagnosed until birth Surgery Cleft lip = at 3 – 6 months (CDC 2018, NHS 2019) Cleft palate = 6 – 12 months Related difficulties? Questions? References Access Excellence (nd) Forms of cell signalling Available at: http://216.98.10.67/RC/VL/GG/ecb/forms_of_cell_signaling.html Board of Regents of the University of Wisconsin (2011) Imaging Planes Available at: https://sites.google.com/site/postgraduatetraining/image-acquisition/the-basics BYJU (nd) Genotype and phenotype difference Available at: https://byjus.com/biology/genotype-and-phenotype-difference/ CDC (2018) Facts about cleft lip and cleft palate Available at: https://www.cdc.gov/ncbddd/birthdefects/cleftlip.html Clancy, J and McVicar AJ (2009) Physiology and anatomy for nurses and healthcare practitioners: A homeostatic approach. Boca Raton: Taylor & Francis Group, LLC Diagnostics (2017) The structure and function of chromatin Available at: https://www.creative- diagnostics.com/blog/index.php/the-structure-and-function-of-chromatin/ FamilyEducation (nd) What color will my baby’s eyes be? A genetic explanation Available at: https://www.familyeducation.com/pregnancy/genetics-and-pregnancy/what-color-will-my-babys-eyes-be-genetic-explanation Graner, J (2010) FMRI scan during working memory tasks Available at: https://commons.wikimedia.org/wiki/File:FMRI_scan_during_working_memory_tasks.jpg References Hughes, Z (2018) Medical Imaging Types and Modalities Available at: https://www.ausmed.co.uk/cpd/articles/medical-imaging- types-and-modalities Institute of Medical Illustrators (2018) IMI National guidelines: A guide to good practice: Cleft lip and palate audit review Available at: https://www.imi.org.uk/wp-content/uploads/2019/01/2018_Sept_IMINatGuidelines_CleftLipPalate_V2-compressed.pdf Khan Academy (nd) Chromosomes Available at: https://www.khanacademy.org/science/high-school-biology/hs-reproduction-and- cell-division/hs-chromosome-structure-and-numbers/a/dna-and-chromosomes-article Marieb, EN and Keller, SM (2018) Essentials of Human Anatomy & Physiology. Harlow: Pearson Education Limited Mayo, H, Punchihewa, H, Emile, J and Morrison, J (2018) Types of Medical Imaging Available at: https://www.doc.ic.ac.uk/~jce317/types-medical-imaging.html National Institutes of Health (2019) What is a gene? Available at: https://ghr.nlm.nih.gov/primer/basics/gene Nature Education (2014) Essentials of Genetics: Unit 1: What is DNA? What does DNA do? Available at: https://www.nature.com/scitable/ebooks/essentials-of-genetics-8/126430897/ NHS (2017) Down’s syndrome Available at: https://www.nhs.uk/conditions/downs-syndrome/ References NHS (2019) Cleft lip and palate Available at: https://www.nhs.uk/conditions/cleft-lip-and-palate/ NHS inform (2019) Down’s syndrome Available at: https://www.nhsinform.scot/illnesses-and-conditions/brain-nerves-and-spinal- cord/downs-syndrome#about-downs-syndrome Nivin, L (nd) The story behind the picture Available at: http://livinsassy.com/2016/03/the-story-behind-that-picture/ O’Neil, D (2012) Sex-linked genes Available at: https://www2.palomar.edu/anthro/biobasis/bio_4.htm Prashanthsaddala (2012) CT of lacunar strokes Available at: https://commons.wikimedia.org/wiki/File:CT_of_lacunar_strokes.jpg Peate, I and Nair, M (2017) Fundamentals of anatomy and physiology: For nursing and healthcare students Chichester: John Wiley & Sons Ltd RegisteredNurseRN.com (no date) Anatomical Position and Directional Terms Available at: https://www.registerednursern.com/anatomical-position-directional-terms/ Rouse, MH (2020) Neuroanatomy for speech-language pathology and audiology Burlington: Jones & Bartlett Learning Today (2018) The first Gerber baby with Down syndrome will steal your heart Available at: https://www.today.com/parents/2018- gerber-baby-first-gerber-baby-down-syndrome-t122258 References Tryphon (2008) Chromosome upright Available at: https://commons.wikimedia.org/wiki/File:Chromosome- upright.png#/media/File:Chromosome.svg Sanko (2011) PET Scan head and neck of nasopharynx carcinoma (NPC) Available at: https://commons.wikimedia.org/wiki/File:PET_Scan_nasopharynx_carcinoma.jpg Seikel, JA, King DW and Drumright, DG (2010) Anatomy & physiology for speech, language, and hearing. New York: Delmar Cengage Learning Soames, R and Palastanga N (2019) Anatomy & Human Movement. Poland: Elsevier UVA Radiology and Medical Imaging (2019) Different imaging tests, explained Available at: https://blog.radiology.virginia.edu/different-imaging-tests-explained/ Group activity