Compendium 12 - How do cells grow, specialise and die (mitosis and meiosis) Flashcards
what atoms does DNA contain
C, H, O, N, P
define nucleotide and nucleoside
nucleoside = pentose sugar + nitrogenous base
nucleotide = nucleoside + phosphate
where is DNA found and what proportion is coding and non coding
- found in nucleus and mitochondria
- 98.5% is non-coding
- 1.5% is coding
what makes up the non coding section of DNA
regulatory sequences, introns, repeat elements
what is the structure of DNA and why first described it
- watson and crick in 1953
it is a double helix twisted around histones
what is a karyotype and what would we typically see when looking at one
it is a map of all the chromosomes in a dividing cell
we would see
- 46 chromosomes (23 pairs)
- 22 pairs are autosomal and 1 pair is sex
what is the structure of RNA and where is it found
- single stranded, self complementary sequences cause folds
- it is found in the nucleus and cytoplasm
what are the 3 main types of RNA and what do they do
messenger RNA - leaves nucleus and contains coding sequence for proteins
transfer RNA - has complementary anticodons and carries a specific amino acid
ribosomal RNA - structure for ribosome
what is a gene and allele
a gene is a small segment of DNA that codes for a protein, an allele is the variation of a gene
what are the 3 types of Amino acids and how many do we have of each
9 essential - must be consumed
5 non-essential - made in the body
6 conditional - not essential but needed in times of illness or stress
what are the 6 main functions proteins in the body
- regulation - enzymes, protein based hormones
- transport - haemoglobin, plasma proteins, cell membrane proteins
- protection - antibodies
- contraction in muscles - actin and myosin
- structure - collagen and keratin
- energy - can be broken down for energy
what are proteins rarely used for energy
because they are needed for so many things in the body, it is a last resort (when no carbs available)
what are the 2 types of proteins and what are characteristics of each
- FIbrous (more structural)
- arranged in parallel along an axis
- usually insoluble in water and stable
- provide mechanical support + tensile strength
- less sensitive to change in temp, pH, etc.
- makes up a lot of the intercellular matrix - Globular (more functional)
- folded into compact ball shape
- crucial role in almost all biological processes
- usually water soluble
- mobile and chemically active
sensitive to chance in temp, pH, etc.
define proteome of a cell, why does it differ between cells
all the proteins that make up a cell, different gene expression in cells causes different proteins to be made
what is the name of the process for DNA > RNA > proteins
Central dogma
what are the names for the 2 stands that make up DNA
- coding strand
- template strand
where does RNA polymerase join and stop during transcription
joins at promoter region
stops at terminator region
what is a ribosome comples
- lost of ribosomes working on the same piece of RNA
how many possible codons are the
64
what are the start and stop codons
start codon = AUG (methionine)
stop codons = UAG, UAA, UGA
what is post translational modification (3)
the chemical modification of a protein after translation, where
-functional groups are added ( lipids and carbs),
-some are cut in half or have AAs cleaved off the end
- phosphorylation - controlling behaviour of proteins (eg. activating or deactivation an enzyme)
what are the 3 categories of cells in the body (haploid?)
somatic - normal body cells, undergo mitosis
germ - give rise to gametes in the gonads, undergo meiosis
gametes - cells that fuse during reproduction (haploid)
define locus
part of a chromosome where a specific gene is located
describe interphase
- cells spend 90% of their time here
-it is split into 3 sections
G1: normal cell activity
S: DNA replicates
G2: enzymes for cell division are produced and organelles are replicated
describe prophase
- centrioles divide and move to each end
- spindle fibres form (some extend towards equator)
- chromatin condenses into chromosomes
- nuclear envelope disappears
describe metaphase
- chromosomes line up along equator
- spindle fibres attach to centromeres
describe anaphase
- centromeres divide and chromatids are pulled apart to each side of the cell
- cytokinesis begins
- phase ends when chromatids reach opposite ends
describe telophase
- nuclear envelope reforms
- cytokinesis continues
- chromosomes start unravelling
- microtubules disappear
describe cytokinesis
cytoplasm and organelles divide
what parts of the body have mitosis occurring slowly
- brain
- heart
- skeletal muscles
what are some examples where mitosis occurs most frequently (5)
- areas of high abrasion
- during pregnancy
- during puberty
- wound healing
- RBCs
what is unique about meiosis prophase 1
chromosome pairs undergo synapsis to for tetrads (sit closely together)
crossing over between homologous chromosomes occurs
what is special about metaphase 1
random assortment along the equator
what are the products at the end of meiosis 1
2 daughter cells each with 23 chromosomes (still replicated) that are not identical
what product are there at the end of meiosis 2
4 daughter cells each with 23 chromosomes (not replicated) that are all unique and haploid
name and describe 2 places where meiosis is occuring
in the testes (spermatogenesis) which is a lifelong process
and in the ovaries (oogenesis)
- at birth they contain all oocytes paused at prophase 1
- 1 division produces 1 function oocyte and 3 polar bodies
