The Cell: Basic Unit Of Plant & Animal Life

The Cell Basic unit of plant & animal life.

Life begins with one cell Zygote – fertilized egg  Embryo – zygote divides and cells multiply 

 Cells

begin to differentiate – change their function  Brain cells, muscle cells, hair, etc. 

Fetus – Foal – Adult  New 

cells still being produced throughout life

RBC, bone, skin, gametes

Differentiated Cells 

100’s of cell types in the body  All

cells have the same genetic information  Function determined by the genes inherited  Certain genetic signals are translated and expressed  Fulfill their role in the body

Cytogenetics 

The branch of biology that deals with heredity and the cellular components, particularly chromosomes associated with inheritance  Genotype

– the exact genetic makeup - full hereditary information of an organism represented by the particular set of genes it possesses.  Phenotype – represents its actual physical properties, such as appearance (height, weight, hair color) and or performance

2 Main Cellular Compartments 

Cytoplasm  Bordered

externally by the plasma membrane (cell membrane) and internally by the nuclear envelope  Area where organelles found 



Mitochondria, Endoplasmic Reticulum, Golgi apparatus, etc

Nucleus  Control

center of the cell – contains all the genetic information in the form of DNA

Mitochondria – energy generator

Nucleolus Nucleus

Endoplasmic Reticulum -Contains Ribosomes Protein synthesis

Genetic Inheritance 

Chromosome  Threadlike

part of a cell that carries hereditary information – DNA – in the form of gene



Gene  Hereditary

unit consisting of a sequence of DNA that occupies a specific location on a chromosome  Determines a particular characteristic in an organism 

Locus (loci – pl)  Specific



location of a gene on a chromosome

Allele  Any

of a number of alternative forms of a gene

Homologous Chromosomes 

Paired – horse = 32 pair (64 individual) 1

paternal and 1 maternal  Similar in length (number of DNA units)  Similar genetic information - genes Allele – variations of specific gene found at particular locus  Homozygous – identical alleles  Heterozygous – different alleles 

How to tell chromosomes apart. 

Centromere  Constriction

in a chromosome that divides it into two

arms  Responsible for proper segregation of each chromosome pair during cell division 

Length of DNA strand  Made

up of units of a base, a sugar and phosphoric

acid  Four bases – (A) adenine, (G) guanine, (T) thymine or (C) cytosine  Order of bases contains code for formation of proteins 

64 different combinations – 20 amino acids

Centromere 

Acrocentric – near one end  36



Metacentric – near middle  26



(18 pair) of the autosomes (non sex chromosomes)

(13 pair) of the autosomes

Telocentric – very close to end

Karyotype

Ex. Human chromosomes (23 pair)

Terms: Mitosis -Prometaphase -Metaphase Homologous Chromosomes Sister Chromatids two identical copies

 

Male sex chromosome (Y) is acrocentric Female sex chromosome (X) is submetacentric